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入门，为开发人员分享快速参考备忘单。">
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<p>提供基本语法和方法的 Elixir 快速参考备忘单。</p>
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</svg></div><div class="menu-modal"><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#入门">入门</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#安装elixir">安装Elixir</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#helloexs">hello.exs</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#基本类型">基本类型</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#基本算术">基本算术</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#布尔算术">布尔算术</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#比较运算符">比较运算符</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#字符串插值与拼接">字符串插值与拼接</a><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#集合">集合</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#列表list">列表（List）</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#元组tuple">元组（Tuple）</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#关键字列表keyword-list">关键字列表（Keyword List）</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#映射map">映射（Map）</a><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#模式匹配">模式匹配</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#匹配操作符">匹配操作符</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#pin操作符">Pin操作符</a><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#控制语句">控制语句</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#case">case</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#cond">cond</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#ifunless">if/unless</a><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#函数">函数</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#匿名函数">匿名函数</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#闭包">闭包</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#命名函数">命名函数</a><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#enumerables-与-streams">Enumerables 与 Streams</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#enum">Enum</a><a aria-hidden="true" class="leve3 tocs-link" data-num="3" href="#stream">Stream</a><a aria-hidden="true" class="leve2 tocs-link" data-num="2" href="#另见">另见</a></div></div><div class="h1wrap-body"><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="入门"><a aria-hidden="true" tabindex="-1" href="#入门"><span class="icon icon-link"></span></a>入门</h2><div class="wrap-body">
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</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="安装elixir"><a aria-hidden="true" tabindex="-1" href="#安装elixir"><span class="icon icon-link"></span></a>安装Elixir</h3><div class="wrap-body">
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<blockquote>
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<p>每个操作系统的安装说明可以在 elixir-lang.org 网站上 <a href="http://elixir-lang.org/install.html">Installing Elixir</a> 部分找到。<br>
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Elixir 自带了<code>iex</code>这样一个交互 shell，可以随时计算 Elixir 表达式的值,运行<code>iex</code>命令，继续输入几个简单的表达式试试：</p>
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</blockquote>
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<pre class="language-shell"><code class="language-shell code-highlight"><span class="code-line">iex <span class="token number">2</span>+3
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</span><span class="code-line"><span class="token number">5</span>
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</span><span class="code-line">iex <span class="token number">2</span>+3 <span class="token operator">==</span> <span class="token number">5</span>
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</span><span class="code-line"><span class="token boolean">true</span>
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</span><span class="code-line">iex String.length<span class="token punctuation">(</span><span class="token string">"The quick brown fox jumps over the lazy dog"</span><span class="token punctuation">)</span>
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</span><span class="code-line"><span class="token number">43</span>
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</span></code></pre>
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</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="helloexs"><a aria-hidden="true" tabindex="-1" href="#helloexs"><span class="icon icon-link"></span></a>hello.exs</h3><div class="wrap-body">
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<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line"><span class="token module class-name">IO</span><span class="token punctuation">.</span><span class="token function">puts</span><span class="token punctuation">(</span><span class="token string">"Hello world from Elixir"</span><span class="token punctuation">)</span>
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</span></code></pre>
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<p>Elixir 运行命令</p>
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<pre class="language-shell"><code class="language-shell code-highlight"><span class="code-line">$ elixir hello.exs
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</span></code></pre>
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</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="基本类型"><a aria-hidden="true" tabindex="-1" href="#基本类型"><span class="icon icon-link"></span></a>基本类型</h3><div class="wrap-body">
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<blockquote>
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<p>Elixir 支持多种基本类型：整数、浮点、布尔值、原子和字符串。其他数据类型，如列表和元组</p>
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</blockquote>
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<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token number">1</span> <span class="token comment"># integer</span>
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</span><span class="code-line">iex<span class="token operator">></span> <span class="token number">0x1F</span> <span class="token comment"># integer（支持二进制、八进制和十六进制的整数）</span>
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</span><span class="code-line">iex<span class="token operator">></span> <span class="token number">1.0</span> <span class="token comment"># float</span>
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</span><span class="code-line">iex<span class="token operator">></span> <span class="token boolean">true</span> <span class="token comment"># boolean</span>
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</span><span class="code-line">iex<span class="token operator">></span> <span class="token atom symbol">:atom</span> <span class="token comment"># atom / symbol</span>
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</span><span class="code-line">iex<span class="token operator">></span> <span class="token string">"elixir"</span> <span class="token comment"># string</span>
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</span><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]</span> <span class="token comment"># list</span>
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</span><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">}</span> <span class="token comment"># tuple</span>
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</span></code></pre>
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</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="基本算术"><a aria-hidden="true" tabindex="-1" href="#基本算术"><span class="icon icon-link"></span></a>基本算术</h3><div class="wrap-body">
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<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token number">1</span> <span class="token operator">+</span> <span class="token number">2</span>
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</span><span class="code-line"><span class="token number">3</span>
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</span><span class="code-line">iex<span class="token operator">></span> <span class="token number">5</span> <span class="token operator">*</span> <span class="token number">5</span>
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</span><span class="code-line"><span class="token number">25</span>
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</span><span class="code-line">iex<span class="token operator">></span> <span class="token number">10</span> <span class="token operator">/</span> <span class="token number">2</span>
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</span><span class="code-line"><span class="token number">5.0</span>
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</span></code></pre>
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<blockquote>
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<p>运算符<code>/</code>总是返回一个float。如果你想做整数除法或得到除法余数，你可以调用div和rem函数:</p>
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</blockquote>
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<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token function">div</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span>
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</span><span class="code-line"><span class="token number">5</span>
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</span><span class="code-line">iex<span class="token operator">></span> div <span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">2</span> <span class="token comment"># Elixir允许在调用需要一个或多个参数的函数时删除括号</span>
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</span><span class="code-line"><span class="token number">5</span>
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</span><span class="code-line">iex<span class="token operator">></span> rem <span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">3</span>
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</span><span class="code-line"><span class="token number">1</span>
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</span></code></pre>
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<blockquote>
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<p>可以调用round函数来获取与给定浮点数最接近的整数，或者调用trunc函数来获取浮点数的整数部分</p>
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</blockquote>
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<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token function">round</span><span class="token punctuation">(</span><span class="token number">3.58</span><span class="token punctuation">)</span>
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</span><span class="code-line"><span class="token number">4</span>
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</span><span class="code-line">iex<span class="token operator">></span> <span class="token function">trunc</span><span class="token punctuation">(</span><span class="token number">3.58</span><span class="token punctuation">)</span>
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</span><span class="code-line"><span class="token number">3</span>
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</span></code></pre>
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<blockquote>
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<p>可以使用is_integer、is_float或is_number分别检查参数是否为integer、float或number类型</p>
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</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token function">is_integer</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token boolean">true</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token function">is_float</span><span class="token punctuation">(</span><span class="token number">2.0</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token boolean">true</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token function">is_number</span><span class="token punctuation">(</span><span class="token number">2.0</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token boolean">false</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="布尔算术"><a aria-hidden="true" tabindex="-1" href="#布尔算术"><span class="icon icon-link"></span></a>布尔算术</h3><div class="wrap-body">
|
||
<blockquote>
|
||
<p>Elixir 提供了 <code>||</code>、<code>&&</code> 和 <code>!</code> 布尔操作符，它们支持任何类型的操作：</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token operator">-</span><span class="token number">20</span> <span class="token operator">||</span> <span class="token boolean">true</span>
|
||
</span><span class="code-line"><span class="token operator">-</span><span class="token number">20</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token boolean">false</span> <span class="token operator">||</span> <span class="token number">42</span>
|
||
</span><span class="code-line"><span class="token number">42</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token number">42</span> <span class="token operator">&&</span> <span class="token boolean">true</span>
|
||
</span><span class="code-line"><span class="token boolean">true</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token number">42</span> <span class="token operator">&&</span> <span class="token boolean">nil</span>
|
||
</span><span class="code-line"><span class="token boolean">nil</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token operator">!</span><span class="token number">42</span>
|
||
</span><span class="code-line"><span class="token boolean">false</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token operator">!</span><span class="token boolean">false</span>
|
||
</span><span class="code-line"><span class="token boolean">true</span>
|
||
</span></code></pre>
|
||
<blockquote>
|
||
<p>还有三个操作符（and、or、not），它们的第一个参数<strong>必须是布尔类型</strong>（true 和 false）:</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token boolean">true</span> <span class="token keyword">and</span> <span class="token number">42</span>
|
||
</span><span class="code-line"><span class="token number">42</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token boolean">false</span> <span class="token keyword">or</span> <span class="token boolean">true</span>
|
||
</span><span class="code-line"><span class="token boolean">true</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token keyword">not</span> <span class="token boolean">false</span>
|
||
</span><span class="code-line"><span class="token boolean">true</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token number">42</span> <span class="token keyword">and</span> <span class="token boolean">true</span>
|
||
</span><span class="code-line"><span class="token operator">*</span><span class="token operator">*</span> <span class="token punctuation">(</span><span class="token module class-name">ArgumentError</span><span class="token punctuation">)</span> argument <span class="token attr-name">error:</span> <span class="token number">42</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token keyword">not</span> <span class="token number">42</span>
|
||
</span><span class="code-line"><span class="token operator">*</span><span class="token operator">*</span> <span class="token punctuation">(</span><span class="token module class-name">ArgumentError</span><span class="token punctuation">)</span> argument error
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="比较运算符"><a aria-hidden="true" tabindex="-1" href="#比较运算符"><span class="icon icon-link"></span></a>比较运算符</h3><div class="wrap-body">
|
||
<blockquote>
|
||
<p>比较运算符 ：<code>==</code>, <code>!=</code>, <code>===</code>, <code>!==</code>, <code><=</code>, <code>>=</code>, <code><</code> 和 <code>></code></p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token number">1</span> <span class="token operator">></span> <span class="token number">2</span>
|
||
</span><span class="code-line"><span class="token boolean">false</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token number">1</span> <span class="token operator">!=</span> <span class="token number">2</span>
|
||
</span><span class="code-line"><span class="token boolean">true</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token number">2</span> <span class="token operator">==</span> <span class="token number">2</span>
|
||
</span><span class="code-line"><span class="token boolean">true</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token number">2</span> <span class="token operator"><=</span> <span class="token number">3</span>
|
||
</span><span class="code-line"><span class="token boolean">true</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="字符串插值与拼接"><a aria-hidden="true" tabindex="-1" href="#字符串插值与拼接"><span class="icon icon-link"></span></a>字符串插值与拼接</h3><div class="wrap-body">
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> name <span class="token operator">=</span> <span class="token string">"Sean"</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token string">"Hello <span class="token interpolation"><span class="token delimiter punctuation">#{</span>name<span class="token delimiter punctuation">}</span></span>"</span>
|
||
</span><span class="code-line"><span class="token string">"Hello Sean"</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token string">"Hello "</span> <span class="token operator"><></span> <span class="token string">"world!"</span>
|
||
</span><span class="code-line"><span class="token string">"Hello world!"</span>
|
||
</span></code></pre>
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="集合"><a aria-hidden="true" tabindex="-1" href="#集合"><span class="icon icon-link"></span></a>集合</h2><div class="wrap-body">
|
||
<blockquote>
|
||
<p>列表（list）、元组（tuple）、关键字列表（keyword list）、映射（map）。</p>
|
||
</blockquote>
|
||
</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="列表list"><a aria-hidden="true" tabindex="-1" href="#列表list"><span class="icon icon-link"></span></a>列表（List）</h3><div class="wrap-body">
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">[</span><span class="token number">3.14</span><span class="token punctuation">,</span> <span class="token atom symbol">:pie</span><span class="token punctuation">,</span> <span class="token string">"Apple"</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line"><span class="token punctuation">[</span><span class="token number">3.14</span><span class="token punctuation">,</span> <span class="token atom symbol">:pie</span><span class="token punctuation">,</span> <span class="token string">"Apple"</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">iex<span class="token operator">></span> list <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">3.14</span><span class="token punctuation">,</span> <span class="token atom symbol">:pie</span><span class="token punctuation">,</span> <span class="token string">"Apple"</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">[</span><span class="token number">3.14</span><span class="token punctuation">,</span> <span class="token atom symbol">:pie</span><span class="token punctuation">,</span> <span class="token string">"Apple"</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">[</span><span class="token string">"π"</span> <span class="token operator">|</span> list<span class="token punctuation">]</span> <span class="token comment"># 列表的开头添加元素</span>
|
||
</span><span class="code-line"><span class="token punctuation">[</span><span class="token string">"π"</span><span class="token punctuation">,</span> <span class="token number">3.14</span><span class="token punctuation">,</span> <span class="token atom symbol">:pie</span><span class="token punctuation">,</span> <span class="token string">"Apple"</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> list <span class="token operator">++</span> <span class="token punctuation">[</span><span class="token string">"Cherry"</span><span class="token punctuation">]</span> <span class="token comment"># 列表的尾部添加元素/列表拼接</span>
|
||
</span><span class="code-line"><span class="token punctuation">[</span><span class="token number">3.14</span><span class="token punctuation">,</span> <span class="token atom symbol">:pie</span><span class="token punctuation">,</span> <span class="token string">"Apple"</span><span class="token punctuation">,</span> <span class="token string">"Cherry"</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">iex<span class="token operator">></span> hd <span class="token punctuation">[</span><span class="token number">3.14</span><span class="token punctuation">,</span> <span class="token atom symbol">:pie</span><span class="token punctuation">,</span> <span class="token string">"Apple"</span><span class="token punctuation">]</span> <span class="token comment"># 获取列表的头部元素</span>
|
||
</span><span class="code-line"><span class="token number">3.14</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> tl <span class="token punctuation">[</span><span class="token number">3.14</span><span class="token punctuation">,</span> <span class="token atom symbol">:pie</span><span class="token punctuation">,</span> <span class="token string">"Apple"</span><span class="token punctuation">]</span> <span class="token comment"># 获取列表的尾部元素</span>
|
||
</span><span class="code-line"><span class="token punctuation">[</span><span class="token atom symbol">:pie</span><span class="token punctuation">,</span> <span class="token string">"Apple"</span><span class="token punctuation">]</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="元组tuple"><a aria-hidden="true" tabindex="-1" href="#元组tuple"><span class="icon icon-link"></span></a>元组（Tuple）</h3><div class="wrap-body">
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">{</span><span class="token number">3.14</span><span class="token punctuation">,</span> <span class="token atom symbol">:pie</span><span class="token punctuation">,</span> <span class="token string">"Apple"</span><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span><span class="token number">3.14</span><span class="token punctuation">,</span> <span class="token atom symbol">:pie</span><span class="token punctuation">,</span> <span class="token string">"Apple"</span><span class="token punctuation">}</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="关键字列表keyword-list"><a aria-hidden="true" tabindex="-1" href="#关键字列表keyword-list"><span class="icon icon-link"></span></a>关键字列表（Keyword List）</h3><div class="wrap-body">
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">[</span><span class="token attr-name">foo:</span> <span class="token string">"bar"</span><span class="token punctuation">,</span> <span class="token attr-name">hello:</span> <span class="token string">"world"</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line"><span class="token punctuation">[</span><span class="token attr-name">foo:</span> <span class="token string">"bar"</span><span class="token punctuation">,</span> <span class="token attr-name">hello:</span> <span class="token string">"world"</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">[</span><span class="token punctuation">{</span><span class="token atom symbol">:foo</span><span class="token punctuation">,</span> <span class="token string">"bar"</span><span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span><span class="token atom symbol">:hello</span><span class="token punctuation">,</span> <span class="token string">"world"</span><span class="token punctuation">}</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line"><span class="token punctuation">[</span><span class="token attr-name">foo:</span> <span class="token string">"bar"</span><span class="token punctuation">,</span> <span class="token attr-name">hello:</span> <span class="token string">"world"</span><span class="token punctuation">]</span>
|
||
</span></code></pre>
|
||
<blockquote>
|
||
<p>关键字列表非常重要，它有以下的特性：</p>
|
||
</blockquote>
|
||
<ul>
|
||
<li>键（key）都是原子（atom）</li>
|
||
<li>键（key）是有序的（定义后，顺序不会改变）</li>
|
||
<li>键（key）不必是唯一的</li>
|
||
</ul>
|
||
<blockquote>
|
||
<p>因为这些原因，关键字列表最常见的用法是作为参数传递给函数。</p>
|
||
</blockquote>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="映射map"><a aria-hidden="true" tabindex="-1" href="#映射map"><span class="icon icon-link"></span></a>映射（Map）</h3><div class="wrap-body">
|
||
<blockquote>
|
||
<p>Elixir 的映射（maps）是键值对结构的第一选择，和关键字列表（keywords）不同，映射允许任意类型的数据作为键，而且数据并不严格排序。 你可以使用 %{} 来定义映射：</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> map <span class="token operator">=</span> <span class="token punctuation">%</span><span class="token punctuation">{</span><span class="token atom symbol">:foo</span> <span class="token operator">=></span> <span class="token string">"bar"</span><span class="token punctuation">,</span> <span class="token string">"hello"</span> <span class="token operator">=></span> <span class="token atom symbol">:world</span><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token punctuation">%</span><span class="token punctuation">{</span><span class="token atom symbol">:foo</span> <span class="token operator">=></span> <span class="token string">"bar"</span><span class="token punctuation">,</span> <span class="token string">"hello"</span> <span class="token operator">=></span> <span class="token atom symbol">:world</span><span class="token punctuation">}</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> map<span class="token punctuation">[</span><span class="token atom symbol">:foo</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line"><span class="token string">"bar"</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> map<span class="token punctuation">[</span><span class="token string">"hello"</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line"><span class="token atom symbol">:world</span>
|
||
</span></code></pre>
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="模式匹配"><a aria-hidden="true" tabindex="-1" href="#模式匹配"><span class="icon icon-link"></span></a>模式匹配</h2><div class="wrap-body">
|
||
<blockquote>
|
||
<p>模式匹配是 Elixir 很强大的特性，它允许我们匹配简单值、数据结构、甚至函数。</p>
|
||
</blockquote>
|
||
</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="匹配操作符"><a aria-hidden="true" tabindex="-1" href="#匹配操作符"><span class="icon icon-link"></span></a>匹配操作符</h3><div class="wrap-body">
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line"><span class="token comment"># 匹配元组</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">{</span>a<span class="token punctuation">,</span> b<span class="token punctuation">,</span> c<span class="token punctuation">}</span> <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token atom symbol">:hello</span><span class="token punctuation">,</span> <span class="token string">"world"</span><span class="token punctuation">,</span> <span class="token number">42</span><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span><span class="token atom symbol">:hello</span><span class="token punctuation">,</span> <span class="token string">"world"</span><span class="token punctuation">,</span> <span class="token number">42</span><span class="token punctuation">}</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> a
|
||
</span><span class="code-line"><span class="token atom symbol">:hello</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> b
|
||
</span><span class="code-line"><span class="token string">"world"</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment"># 匹配列表</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">[</span>a<span class="token punctuation">,</span> b<span class="token punctuation">,</span> c<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line"><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> a
|
||
</span><span class="code-line"><span class="token number">1</span>
|
||
</span><span class="code-line"><span class="token comment"># 匹配列表的头部元素</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">[</span>head <span class="token operator">|</span> tail<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line"><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> head
|
||
</span><span class="code-line"><span class="token number">1</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> tail
|
||
</span><span class="code-line"><span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="pin操作符"><a aria-hidden="true" tabindex="-1" href="#pin操作符"><span class="icon icon-link"></span></a>Pin操作符</h3><div class="wrap-body">
|
||
<blockquote>
|
||
<p>pin 操作符，就是用已经绑定的值去匹配，而不是重新绑定一个新值。</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">{</span>x<span class="token punctuation">,</span> <span class="token operator">^</span>x<span class="token punctuation">}</span> <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token punctuation">{</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">}</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> x
|
||
</span><span class="code-line"><span class="token number">2</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment"># 使用下划线_忽略匹配的值</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token punctuation">[</span>head <span class="token operator">|</span> _<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line"><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> head
|
||
</span><span class="code-line"><span class="token number">1</span>
|
||
</span></code></pre>
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="控制语句"><a aria-hidden="true" tabindex="-1" href="#控制语句"><span class="icon icon-link"></span></a>控制语句</h2><div class="wrap-body">
|
||
<blockquote>
|
||
<p>case, cond, and if</p>
|
||
</blockquote>
|
||
</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="case"><a aria-hidden="true" tabindex="-1" href="#case"><span class="icon icon-link"></span></a>case</h3><div class="wrap-body">
|
||
<blockquote>
|
||
<p>case允许我们将一个值与许多模式进行比较，直到找到匹配的模式：</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token keyword">case</span> <span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">}</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token punctuation">{</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">6</span><span class="token punctuation">}</span> <span class="token operator">-></span>
|
||
</span><span class="code-line"> <span class="token string">"This clause won't match"</span>
|
||
</span><span class="code-line"> <span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span> x<span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">}</span> <span class="token operator">-></span>
|
||
</span><span class="code-line"> <span class="token string">"This clause will match and bind x to 2 in this clause"</span>
|
||
</span><span class="code-line"> _ <span class="token operator">-></span>
|
||
</span><span class="code-line"> <span class="token string">"This clause would match any value"</span>
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span><span class="code-line"><span class="token string">"This clause will match and bind x to 2 in this clause"</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment"># 还可以使用when指定额外的条件</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token keyword">case</span> <span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">}</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span> x<span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">}</span> <span class="token keyword">when</span> x <span class="token operator">></span> <span class="token number">0</span> <span class="token operator">-></span>
|
||
</span><span class="code-line"> <span class="token string">"Will match"</span>
|
||
</span><span class="code-line"> _ <span class="token operator">-></span>
|
||
</span><span class="code-line"> <span class="token string">"Would match, if guard condition were not satisfied"</span>
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span><span class="code-line"><span class="token string">"Will match"</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="cond"><a aria-hidden="true" tabindex="-1" href="#cond"><span class="icon icon-link"></span></a>cond</h3><div class="wrap-body">
|
||
<blockquote>
|
||
<p>当我们需要匹配条件而不是值的时候，可以使用 cond，这和其他语言的 else if 或者 elsif 相似</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token keyword">cond</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token number">2</span> <span class="token operator">+</span> <span class="token number">2</span> <span class="token operator">==</span> <span class="token number">5</span> <span class="token operator">-></span>
|
||
</span><span class="code-line"> <span class="token string">"This will not be true"</span>
|
||
</span><span class="code-line"> <span class="token number">2</span> <span class="token operator">*</span> <span class="token number">2</span> <span class="token operator">==</span> <span class="token number">3</span> <span class="token operator">-></span>
|
||
</span><span class="code-line"> <span class="token string">"Nor this"</span>
|
||
</span><span class="code-line"> <span class="token number">1</span> <span class="token operator">+</span> <span class="token number">1</span> <span class="token operator">==</span> <span class="token number">2</span> <span class="token operator">-></span>
|
||
</span><span class="code-line"> <span class="token string">"But this will"</span>
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span><span class="code-line"><span class="token string">"But this will"</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment"># 如果所有的条件都返回nil或false，则会引发一个错误（CondClauseError）。因此，需要添加一个final条件，等于true，它将始终匹配：</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token keyword">cond</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token number">2</span> <span class="token operator">+</span> <span class="token number">2</span> <span class="token operator">==</span> <span class="token number">5</span> <span class="token operator">-></span>
|
||
</span><span class="code-line"> <span class="token string">"This is never true"</span>
|
||
</span><span class="code-line"> <span class="token number">2</span> <span class="token operator">*</span> <span class="token number">2</span> <span class="token operator">==</span> <span class="token number">3</span> <span class="token operator">-></span>
|
||
</span><span class="code-line"> <span class="token string">"Nor this"</span>
|
||
</span><span class="code-line"> <span class="token boolean">true</span> <span class="token operator">-></span>
|
||
</span><span class="code-line"> <span class="token string">"This is always true (equivalent to else)"</span>
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span><span class="code-line"><span class="token string">"This is always true (equivalent to else)"</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="ifunless"><a aria-hidden="true" tabindex="-1" href="#ifunless"><span class="icon icon-link"></span></a>if/unless</h3><div class="wrap-body">
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token keyword">if</span> <span class="token boolean">true</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token string">"This works!"</span>
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span><span class="code-line"><span class="token string">"This works!"</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token keyword">unless</span> <span class="token boolean">true</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token string">"This will never be seen"</span>
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span><span class="code-line"><span class="token boolean">nil</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment"># if...else...</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token keyword">if</span> <span class="token boolean">nil</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token string">"This won't be seen"</span>
|
||
</span><span class="code-line"><span class="token keyword">else</span>
|
||
</span><span class="code-line"> <span class="token string">"This will"</span>
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span><span class="code-line"><span class="token string">"This will"</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment"># 关于Elixir中变量的作用域：如果在if、case和类似的构造中声明或更改了任何变量，则声明和更改将只在构造中可见。</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> x <span class="token operator">=</span> <span class="token number">1</span>
|
||
</span><span class="code-line"><span class="token number">1</span>
|
||
</span><span class="code-line"><span class="token keyword">if</span> <span class="token boolean">true</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> x <span class="token operator">=</span> x <span class="token operator">+</span> <span class="token number">1</span>
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span><span class="code-line"><span class="token number">2</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> x
|
||
</span><span class="code-line"><span class="token number">1</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment"># 如果要更改值，则必须从if返回值：</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> x <span class="token operator">=</span> <span class="token number">1</span>
|
||
</span><span class="code-line"><span class="token number">1</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> x <span class="token operator">=</span> <span class="token keyword">if</span> <span class="token boolean">true</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> x <span class="token operator">+</span> <span class="token number">1</span>
|
||
</span><span class="code-line"><span class="token keyword">else</span>
|
||
</span><span class="code-line"> x
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span><span class="code-line"><span class="token number">2</span>
|
||
</span></code></pre>
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="函数"><a aria-hidden="true" tabindex="-1" href="#函数"><span class="icon icon-link"></span></a>函数</h2><div class="wrap-body">
|
||
</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="匿名函数"><a aria-hidden="true" tabindex="-1" href="#匿名函数"><span class="icon icon-link"></span></a>匿名函数</h3><div class="wrap-body">
|
||
<blockquote>
|
||
<p>使用 fn 和 end 关键字来定义匿名函数，在这两者之间，可以定义任意数量的参数和函数体，它们用 -> 分隔开。</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> sum <span class="token operator">=</span> <span class="token function">fn</span> <span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span> <span class="token operator">-></span> a <span class="token operator">+</span> b <span class="token keyword">end</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token function">sum</span><span class="token punctuation">.</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token number">5</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment"># 可以使用 & 语法来简化匿名函数的定义：</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> sum <span class="token operator">=</span> <span class="token operator">&</span><span class="token punctuation">(</span><span class="token argument variable">&1</span> <span class="token operator">+</span> <span class="token argument variable">&2</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token function">sum</span><span class="token punctuation">.</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token number">5</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="闭包"><a aria-hidden="true" tabindex="-1" href="#闭包"><span class="icon icon-link"></span></a>闭包</h3><div class="wrap-body">
|
||
<blockquote>
|
||
<p>匿名函数去引用外部的变量，这通常被称为闭包。</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> double <span class="token operator">=</span> <span class="token keyword">fn</span> a <span class="token operator">-></span> <span class="token function">add</span><span class="token punctuation">.</span><span class="token punctuation">(</span>a<span class="token punctuation">,</span> a<span class="token punctuation">)</span> <span class="token keyword">end</span>
|
||
</span><span class="code-line"><span class="token comment">#Function<6.71889879/1 in :erl_eval.expr/5></span>
|
||
</span><span class="code-line"><span class="token function">double</span><span class="token punctuation">.</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token number">4</span>
|
||
</span></code></pre>
|
||
<blockquote>
|
||
<p>闭包与守卫</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> f <span class="token operator">=</span> <span class="token keyword">fn</span>
|
||
</span><span class="code-line"> x<span class="token punctuation">,</span> y <span class="token keyword">when</span> x <span class="token operator">></span> <span class="token number">0</span> <span class="token operator">-></span> x <span class="token operator">+</span> y
|
||
</span><span class="code-line"> x<span class="token punctuation">,</span> y <span class="token operator">-></span> x <span class="token operator">*</span> y
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token function">f</span><span class="token punctuation">.</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token number">4</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token function">f</span><span class="token punctuation">.</span><span class="token punctuation">(</span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token operator">-</span><span class="token number">3</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="命名函数"><a aria-hidden="true" tabindex="-1" href="#命名函数"><span class="icon icon-link"></span></a>命名函数</h3><div class="wrap-body">
|
||
<blockquote>
|
||
<p>命名函数是通过 def 关键字定义在某个模块中</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line"><span class="token keyword">defmodule</span> <span class="token module class-name">Greeter</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token keyword">def</span> <span class="token function">hello</span><span class="token punctuation">(</span>name<span class="token punctuation">)</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token string">"Hello, "</span> <span class="token operator"><></span> name
|
||
</span><span class="code-line"> <span class="token keyword">end</span>
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token module class-name">Greeter</span><span class="token punctuation">.</span><span class="token function">hello</span><span class="token punctuation">(</span><span class="token string">"Sean"</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token string">"Hello, Sean"</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment"># 简写为一行：</span>
|
||
</span><span class="code-line"><span class="token keyword">defmodule</span> <span class="token module class-name">Greeter</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token keyword">def</span> <span class="token function">hello</span><span class="token punctuation">(</span>name<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token attr-name">do:</span> <span class="token string">"Hello, "</span> <span class="token operator"><></span> name
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment"># 私有函数</span>
|
||
</span><span class="code-line"><span class="token keyword">defmodule</span> <span class="token module class-name">Greeter</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token keyword">def</span> <span class="token function">hello</span><span class="token punctuation">(</span>name<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token attr-name">do:</span> phrase <span class="token operator"><></span> name
|
||
</span><span class="code-line"> <span class="token keyword">defp</span> phrase<span class="token punctuation">,</span> <span class="token attr-name">do:</span> <span class="token string">"Hello, "</span> <span class="token comment"># 使用defp来定义私有函数</span>
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span></code></pre>
|
||
<blockquote>
|
||
<p>函数的默认参数：使用<code>\\</code>来定义默认参数</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line"><span class="token keyword">defmodule</span> <span class="token module class-name">Greeter</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token keyword">def</span> <span class="token function">hello</span><span class="token punctuation">(</span>name<span class="token punctuation">,</span> language_code <span class="token operator">\\</span> <span class="token string">"en"</span><span class="token punctuation">)</span> <span class="token keyword">do</span>
|
||
</span><span class="code-line"> <span class="token function">phrase</span><span class="token punctuation">(</span>language_code<span class="token punctuation">)</span> <span class="token operator"><></span> name
|
||
</span><span class="code-line"> <span class="token keyword">end</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"> <span class="token keyword">defp</span> <span class="token function">phrase</span><span class="token punctuation">(</span><span class="token string">"en"</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token attr-name">do:</span> <span class="token string">"Hello, "</span>
|
||
</span><span class="code-line"> <span class="token keyword">defp</span> <span class="token function">phrase</span><span class="token punctuation">(</span><span class="token string">"es"</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token attr-name">do:</span> <span class="token string">"Hola, "</span>
|
||
</span><span class="code-line"><span class="token keyword">end</span>
|
||
</span></code></pre>
|
||
</div></div></div></div></div><div class="wrap h2body-exist"><div class="wrap-header h2wrap"><h2 id="enumerables-与-streams"><a aria-hidden="true" tabindex="-1" href="#enumerables-与-streams"><span class="icon icon-link"></span></a>Enumerables 与 Streams</h2><div class="wrap-body">
|
||
<blockquote>
|
||
<p>Elixir 提供了 Enum 和 Stream 两个模块，用于处理集合。</p>
|
||
</blockquote>
|
||
</div></div><div class="h2wrap-body"><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="enum"><a aria-hidden="true" tabindex="-1" href="#enum"><span class="icon icon-link"></span></a>Enum</h3><div class="wrap-body">
|
||
<blockquote>
|
||
<p>Enum 模块提供了对集合的常用操作，如 map、filter、reduce、sort、chunk、join、into 等。</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token module class-name">Enum</span><span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">]</span><span class="token punctuation">,</span> <span class="token keyword">fn</span> x <span class="token operator">-></span> x <span class="token operator">*</span> <span class="token number">2</span> <span class="token keyword">end</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">6</span><span class="token punctuation">]</span>
|
||
</span><span class="code-line">iex<span class="token operator">></span> <span class="token module class-name">Enum</span><span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token punctuation">%</span><span class="token punctuation">{</span><span class="token number">1</span> <span class="token operator">=></span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span> <span class="token operator">=></span> <span class="token number">4</span><span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token keyword">fn</span> <span class="token punctuation">{</span>k<span class="token punctuation">,</span> v<span class="token punctuation">}</span> <span class="token operator">-></span> k <span class="token operator">*</span> v <span class="token keyword">end</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">12</span><span class="token punctuation">]</span>
|
||
</span></code></pre>
|
||
</div></div></div><div class="wrap h3body-not-exist"><div class="wrap-header h3wrap"><h3 id="stream"><a aria-hidden="true" tabindex="-1" href="#stream"><span class="icon icon-link"></span></a>Stream</h3><div class="wrap-body">
|
||
<blockquote>
|
||
<p>作为Enum的替代品，Elixir提供了支持懒惰操作的Stream模块</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> <span class="token number">1</span><span class="token operator">..</span><span class="token number">100_000</span> <span class="token operator">|></span> <span class="token module class-name">Stream</span><span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token operator">&</span><span class="token punctuation">(</span><span class="token argument variable">&1</span> <span class="token operator">*</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token operator">|></span> <span class="token module class-name">Stream</span><span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>odd?<span class="token punctuation">)</span> <span class="token operator">|></span> <span class="token module class-name">Enum</span><span class="token punctuation">.</span><span class="token function">sum</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token number">7500000000</span>
|
||
</span></code></pre>
|
||
<blockquote>
|
||
<p>流文件操作</p>
|
||
</blockquote>
|
||
<pre class="language-elixir"><code class="language-elixir code-highlight"><span class="code-line">iex<span class="token operator">></span> stream <span class="token operator">=</span> <span class="token module class-name">File</span><span class="token punctuation">.</span><span class="token function">stream!</span><span class="token punctuation">(</span><span class="token string">"path/to/file"</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line"><span class="token punctuation">%</span><span class="token module class-name">File</span><span class="token punctuation">.</span><span class="token module class-name">Stream</span><span class="token punctuation">{</span>
|
||
</span><span class="code-line"> <span class="token attr-name">line_or_bytes:</span> <span class="token atom symbol">:line</span><span class="token punctuation">,</span>
|
||
</span><span class="code-line"> <span class="token attr-name">modes:</span> <span class="token punctuation">[</span><span class="token atom symbol">:raw</span><span class="token punctuation">,</span> <span class="token atom symbol">:read_ahead</span><span class="token punctuation">,</span> <span class="token atom symbol">:binary</span><span class="token punctuation">]</span><span class="token punctuation">,</span>
|
||
</span><span class="code-line"> <span class="token attr-name">path:</span> <span class="token string">"path/to/file"</span><span class="token punctuation">,</span>
|
||
</span><span class="code-line"> <span class="token attr-name">raw:</span> <span class="token boolean">true</span>
|
||
</span><span class="code-line"><span class="token punctuation">}</span>
|
||
</span><span class="code-line"><span class="token module class-name">Enum</span><span class="token punctuation">.</span><span class="token function">take</span><span class="token punctuation">(</span>stream<span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">)</span>
|
||
</span><span class="code-line">
|
||
</span><span class="code-line"><span class="token comment"># 上面的例子将提取所选文件的前10行。这意味着流对于处理大型文件甚至是网络资源等慢速资源非常有用。</span>
|
||
</span></code></pre>
|
||
</div></div></div></div></div><div class="wrap h2body-not-exist"><div class="wrap-header h2wrap"><h2 id="另见"><a aria-hidden="true" tabindex="-1" href="#另见"><span class="icon icon-link"></span></a>另见</h2><div class="wrap-body">
|
||
<ul>
|
||
<li><a href="https://elixir-lang.org/">Elixir 官方</a> <em>(elixir-lang.org)</em></li>
|
||
<li><a href="https://elixirschool.com/">Elixir School</a> <em>(elixirschool.com)</em></li>
|
||
</ul>
|
||
</div></div><div class="h2wrap-body"></div></div></div><script src="https://giscus.app/client.js" data-repo="jaywcjlove/reference" data-repo-id="R_kgDOID2-Mw" data-category="Q&A" data-category-id="DIC_kwDOID2-M84CS5wo" data-mapping="pathname" data-strict="0" data-reactions-enabled="1" data-emit-metadata="0" data-input-position="bottom" data-theme="dark" data-lang="zh-CN" crossorigin="anonymous" async></script><div class="giscus"></div></div><footer class="footer-wrap"><footer class="max-container">© 2022 <a href="https://wangchujiang.com/#/app" target="_blank">Kenny Wang</a>.</footer></footer><script src="../data.js?v=1.5.3" defer></script><script src="../js/fuse.min.js?v=1.5.3" defer></script><script src="../js/main.js?v=1.5.3" defer></script><div id="mysearch"><div class="mysearch-box"><div class="mysearch-input"><div><svg xmlns="http://www.w3.org/2000/svg" height="1em" width="1em" viewBox="0 0 18 18">
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