<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="x-ua-compatible" content="ie=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="generator" content="ExDoc v0.19.1">
<title>Unicode Syntax – Elixir v1.7.2</title>
<link rel="stylesheet" href="dist/app-240d7fc7e5.css" />
<link rel="canonical" href="https://hexdocs.pm/elixir/v1.7/unicode-syntax.html" />
<script src="dist/sidebar_items-cdf4e58b19.js"></script>
</head>
<body data-type="extras">
<script>try { if(localStorage.getItem('night-mode')) document.body.className += ' night-mode'; } catch (e) { }</script>
<div class="main">
<button class="sidebar-button sidebar-toggle">
<span class="icon-menu" aria-hidden="true"></span>
<span class="sr-only">Toggle Sidebar</span>
</button>
<button class="sidebar-button night-mode-toggle">
<span class="icon-theme" aria-hidden="true"></span>
<span class="sr-only">Toggle Theme</span>
</button>
<section class="sidebar">
<a href="http://elixir-lang.org/docs.html" class="sidebar-projectLink">
<div class="sidebar-projectDetails">
<h1 class="sidebar-projectName">
Elixir </h1>
<h2 class="sidebar-projectVersion">
v1.7.2
</h2>
</div>
<img src="assets/logo.png" alt="Elixir" class="sidebar-projectImage">
</a>
<form class="sidebar-search" action="search.html">
<button type="submit" class="search-button">
<span class="icon-search" aria-hidden="true"></span>
</button>
<input name="q" type="text" id="search-list" class="search-input" placeholder="Search" aria-label="Search" autocomplete="off" />
</form>
<ul class="sidebar-listNav">
<li><a id="extras-list" href="#full-list">Pages</a></li>
<li><a id="modules-list" href="#full-list">Modules</a></li>
<li><a id="exceptions-list" href="#full-list">Exceptions</a></li>
</ul>
<div class="gradient"></div>
<ul id="full-list" class="sidebar-fullList"></ul>
</section>
<section class="content">
<div class="content-outer">
<div id="content" class="content-inner">
<h1>Unicode Syntax</h1>
<p>Elixir supports Unicode throughout the language.</p>
<p>Quoted identifiers, such as strings (<code class="inline">"olá"</code>) and charlists (<code class="inline">'olá'</code>), support Unicode since Elixir v1.0. Strings are UTF-8 encoded. Charlists are lists of Unicode codepoints. In such cases, the contents are kept as written by developers, without any transformation.</p>
<p>Elixir also supports Unicode in identifiers since Elixir v1.5, as defined in the <a href="http://unicode.org/reports/tr31/">Unicode Annex #31</a>. The focus of this document is to describe how Elixir implements the requirements outlined in the Unicode Annex. These requirements are referred to as R1, R6 and so on.</p>
<p>To check the Unicode version of your current Elixir installation, run <code class="inline">String.Unicode.version()</code>.</p>
<h2 id="r1-default-identifiers" class="section-heading">
<a href="#r1-default-identifiers" class="hover-link"><span class="icon-link" aria-hidden="true"></span></a>
R1. Default Identifiers
</h2>
<p>The general Elixir identifier rule is specified as:</p>
<pre><code class="nohighlight makeup elixir"><span class="o"><</span><span class="nc">Identifier</span><span class="o">></span><span class="w"> </span><span class="ss">:=</span><span class="w"> </span><span class="o"><</span><span class="nc">Start</span><span class="o">></span><span class="w"> </span><span class="o"><</span><span class="nc">Continue</span><span class="o">></span><span class="o">*</span><span class="w"> </span><span class="o"><</span><span class="nc">Ending</span><span class="o">></span><span class="err">?</span></code></pre>
<p>where <code class="inline"><Start></code> uses the same categories as the spec but restricts them to the NFC form (see R6):</p>
<blockquote><p>characters derived from the Unicode General Category of uppercase letters, lowercase letters, titlecase letters, modifier letters, other letters, letter numbers, plus <code class="inline">Other_ID_Start</code>, minus <code class="inline">Pattern_Syntax</code> and <code class="inline">Pattern_White_Space</code> code points</p>
<p>In set notation: <code class="inline">[\p{L}\p{Nl}\p{Other_ID_Start}-\p{Pattern_Syntax}-\p{Pattern_White_Space}]</code></p>
</blockquote>
<p>and <code class="inline"><Continue></code> uses the same categories as the spec but restricts them to the NFC form (see R6):</p>
<blockquote><p>ID_Start characters, plus characters having the Unicode General Category of nonspacing marks, spacing combining marks, decimal number, connector punctuation, plus <code class="inline">Other_ID_Continue</code>, minus <code class="inline">Pattern_Syntax</code> and <code class="inline">Pattern_White_Space</code> code points.</p>
<p>In set notation: <code class="inline">[\p{ID_Start}\p{Mn}\p{Mc}\p{Nd}\p{Pc}\p{Other_ID_Continue}-\p{Pattern_Syntax}-\p{Pattern_White_Space}]</code></p>
</blockquote>
<p><code class="inline"><Ending></code> is an addition specific to Elixir that includes only the codepoints <code class="inline">?</code> (003F) and <code class="inline">!</code> (0021).</p>
<p>The spec also provides a <code class="inline"><Medial></code> set but Elixir does not include any character on this set. Therefore the identifier rule has been simplified to consider this.</p>
<p>Elixir does not allow the use of ZWJ or ZWNJ in identifiers and therefore does not implement R1a. R1b is guaranteed for backwards compatibility purposes.</p>
<h3 id="atoms" class="section-heading">
<a href="#atoms" class="hover-link"><span class="icon-link" aria-hidden="true"></span></a>
Atoms
</h3>
<p>Atoms in Elixir follow the identifier rule above with the following modifications:</p>
<ul>
<li><code class="inline"><Start></code> includes the codepoint <code class="inline">_</code> (005F)
</li>
<li><code class="inline"><Continue></code> includes the codepoint <code class="inline">@</code> (0040)
</li>
</ul>
<h3 id="variables" class="section-heading">
<a href="#variables" class="hover-link"><span class="icon-link" aria-hidden="true"></span></a>
Variables
</h3>
<p>Variables in Elixir follow the identifier rule above with the following modifications:</p>
<ul>
<li><code class="inline"><Start></code> includes the codepoint <code class="inline">_</code> (005F)
</li>
<li><code class="inline"><Start></code> must not include Lu (letter uppercase) and Lt (letter titlecase) characters
</li>
</ul>
<h2 id="r3-pattern_white_space-and-pattern_syntax-characters" class="section-heading">
<a href="#r3-pattern_white_space-and-pattern_syntax-characters" class="hover-link"><span class="icon-link" aria-hidden="true"></span></a>
R3. Pattern_White_Space and Pattern_Syntax Characters
</h2>
<p>Elixir supports only codepoints <code class="inline">\t</code> (0009), <code class="inline">\n</code> (000A), <code class="inline">\r</code> (000D) and <code class="inline">\s</code> (0020) as whitespace and therefore does not follow requirement R3. R3 requires a wider variety of whitespace and syntax characters to be supported.</p>
<h2 id="r6-filtered-normalized-identifiers" class="section-heading">
<a href="#r6-filtered-normalized-identifiers" class="hover-link"><span class="icon-link" aria-hidden="true"></span></a>
R6. Filtered Normalized Identifiers
</h2>
<p>Identifiers in Elixir are case sensitive.</p>
<p>Elixir requires all atoms and variables to be in NFC form. Any other form will fail with a relevant error message. Quoted-atoms and strings can, however, be in any form and are not verified by the parser.</p>
<p>In other words, the atom <code class="inline">:josé</code> can only be written with the codepoints <code class="inline">006A 006F 0073 00E9</code>. Using another normalization form will lead to a tokenizer error. On the other hand, <code class="inline">:"josé"</code> may be written as <code class="inline">006A 006F 0073 00E9</code> or <code class="inline">006A 006F 0073 0065 0301</code>, since it is written between quotes.</p>
<p>Choosing requirement R6 automatically excludes requirements R4, R5 and R7.</p>
<footer class="footer">
<p>
<span class="line">
Built using
<a href="https://github.com/elixir-lang/ex_doc" title="ExDoc" target="_blank" rel="help noopener">ExDoc</a> (v0.19.1),
</span>
<span class="line">
designed by
<a href="https://twitter.com/dignifiedquire" target="_blank" rel="noopener" title="@dignifiedquire">Friedel Ziegelmayer</a>.
</span>
</p>
</footer>
</div>
</div>
</section>
</div>
<script src="dist/app-a0c90688fa.js"></script>
</body>
</html>
distrib
>
Mageia
>
7
>
i586
>
media
>
core-release
>
by-pkgid
>
016232f1d9a3f7bee85855d35a2bca58
>
files
>
151
