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<h1>stdlib 41.2.4</h1>

<li><a href="../index.html">Index</a></li>

<h2>Contents</h2>

<li><a href="#Functions">Functions</a></li>

<h2>Modules</h2>

<ul class="nowrap">

<li><a href="../modules/std.html">std</a></li>

<li><a href="../modules/std.debug.html">std.debug</a></li>

<li><a href="../modules/std.functional.html">std.functional</a></li>

<li><a href="../modules/std.io.html">std.io</a></li>

<li><a href="../modules/std.math.html">std.math</a></li>

<li><strong>std.operator</strong></li>

<li><a href="../modules/std.package.html">std.package</a></li>

<li><a href="../modules/std.strict.html">std.strict</a></li>

<li><a href="../modules/std.string.html">std.string</a></li>

<li><a href="../modules/std.table.html">std.table</a></li>

<h2>Classes</h2>

<ul class="nowrap">

<li><a href="../classes/std.tree.html">std.tree</a></li>

<li><a href="../classes/std.container.html">std.container</a></li>

<li><a href="../classes/std.object.html">std.object</a></li>

<li><a href="../classes/std.list.html">std.list</a></li>

<li><a href="../classes/std.optparse.html">std.optparse</a></li>

<li><a href="../classes/std.set.html">std.set</a></li>

<li><a href="../classes/std.strbuf.html">std.strbuf</a></li>

<div id="content">

<h1>Module <code>std.operator</code></h1>

<p>Functional forms of Lua operators.</p>

<h2><a href="#Functions">Functions</a></h2>

<table class="function_list">

<tr>

<td class="name" nowrap><a href="#concat">concat (a, b)</a></td>

<td class="summary">Stringify and concatenate arguments.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#conj">conj (a, b)</a></td>

<td class="summary">Return the logical conjunction of the arguments.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#diff">diff (a, b)</a></td>

<td class="summary">Return the difference of the arguments.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#disj">disj (a, b)</a></td>

<td class="summary">Return the logical disjunction of the arguments.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#eq">eq (a, b)</a></td>

<td class="summary">Return the equality of the arguments.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#get">get (t, k)</a></td>

<td class="summary">Dereference a table.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#gt">gt (a, b)</a></td>

<td class="summary">Return whether the arguments are in descending order.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#gte">gte (a, b)</a></td>

<td class="summary">Return whether the arguments are not in ascending order.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#lt">lt (a, b)</a></td>

<td class="summary">Return whether the arguments are in ascending order.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#lte">lte (a, b)</a></td>

<td class="summary">Return whether the arguments are not in descending order.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#mod">mod (a, b)</a></td>

<td class="summary">Return the modulus of the arguments.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#neg">neg (a)</a></td>

<td class="summary">Return the logical negation of the arguments.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#neq">neq (a, b)</a></td>

<td class="summary">Return the inequality of the arguments.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#pow">pow (a, b)</a></td>

<td class="summary">Return the exponent of the arguments.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#prod">prod (a, b)</a></td>

<td class="summary">Return the product of the arguments.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#quot">quot (a, b)</a></td>

<td class="summary">Return the quotient of the arguments.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#set">set (t, k, v)</a></td>

<td class="summary">Set a table element, honoring metamethods.</td>

</tr>

<tr>

<td class="name" nowrap><a href="#sum">sum (a, b)</a></td>

<td class="summary">Return the sum of the arguments.</td>

</tr>

<h2 class="section-header "><a name="Functions"></a>Functions</h2>

Methods

<dl class="function">

<dt>

<a name = "concat"></a>

<strong>concat (a, b)</strong>

</dt>

<dd>

Stringify and concatenate arguments.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

concatenation of stringified arguments.

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">--&gt; "=&gt; 1000010010"

</span>functional.<span class="function-name">foldl</span> (concat, <span class="string">"=&gt; "</span>, {<span class="number">10000</span>, <span class="number">100</span>, <span class="number">10</span>})</pre>

</ul>

<dt>

<a name = "conj"></a>

<strong>conj (a, b)</strong>

</dt>

<dd>

Return the logical conjunction of the arguments.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

logical <em>a</em> and <em>b</em>

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">--&gt; true

</span>functional.<span class="function-name">foldl</span> (conj, {<span class="keyword">true</span>, <span class="number">1</span>, <span class="string">"false"</span>})</pre>

</ul>

<dt>

<a name = "diff"></a>

<strong>diff (a, b)</strong>

</dt>

<dd>

Return the difference of the arguments.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

the difference between <em>a</em> and <em>b</em>

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">--&gt; 890

</span>functional.<span class="function-name">foldl</span> (diff, {<span class="number">10000</span>, <span class="number">100</span>, <span class="number">10</span>})</pre>

</ul>

<dt>

<a name = "disj"></a>

<strong>disj (a, b)</strong>

</dt>

<dd>

Return the logical disjunction of the arguments.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

logical <em>a</em> or <em>b</em>

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">--&gt; true

</span>functional.<span class="function-name">foldl</span> (disj, {<span class="keyword">true</span>, <span class="number">1</span>, <span class="keyword">false</span>})</pre>

</ul>

<dt>

<a name = "eq"></a>

<strong>eq (a, b)</strong>

</dt>

<dd>

Return the equality of the arguments.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

<code>true</code> if <em>a</em> is <em>b</em>, otherwise <code>false</code>

</ol>

<dt>

<a name = "get"></a>

<strong>get (t, k)</strong>

</dt>

<dd>

Dereference a table.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">t</span>

<span class="types"><a class="type" href="https://www.lua.org/manual/5.1/manual.html#5.5">table</a></span>

a table

</li>

<li><span class="parameter">k</span>

a key to lookup in <em>t</em>

</li>

</ul>

<h3>Returns:</h3>

<ol>

value stored at <em>t[k]</em> if any, otherwise <code>nil</code>

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">--&gt; 4

</span>functional.<span class="function-name">foldl</span> (get, {<span class="number">1</span>, {{<span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>}, <span class="number">5</span>}}, {<span class="number">2</span>, <span class="number">1</span>, <span class="number">3</span>})</pre>

</ul>

<dt>

<a name = "gt"></a>

<strong>gt (a, b)</strong>

</dt>

<dd>

Return whether the arguments are in descending order.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

<code>true</code> if <em>a</em> is greater then <em>b</em>, otherwise <code>false</code>

</ol>

<dt>

<a name = "gte"></a>

<strong>gte (a, b)</strong>

</dt>

<dd>

Return whether the arguments are not in ascending order.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

<code>true</code> if <em>a</em> is not greater then <em>b</em>, otherwise <code>false</code>

</ol>

<dt>

<a name = "lt"></a>

<strong>lt (a, b)</strong>

</dt>

<dd>

Return whether the arguments are in ascending order.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

<code>true</code> if <em>a</em> is less then <em>b</em>, otherwise <code>false</code>

</ol>

<dt>

<a name = "lte"></a>

<strong>lte (a, b)</strong>

</dt>

<dd>

Return whether the arguments are not in descending order.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

<code>true</code> if <em>a</em> is not greater then <em>b</em>, otherwise <code>false</code>

</ol>

<dt>

<a name = "mod"></a>

<strong>mod (a, b)</strong>

</dt>

<dd>

Return the modulus of the arguments.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

the modulus of <em>a</em> and <em>b</em>

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">--&gt; 3

</span>functional.<span class="function-name">foldl</span> (mod, {<span class="number">65536</span>, <span class="number">100</span>, <span class="number">11</span>})</pre>

</ul>

<dt>

<a name = "neg"></a>

<strong>neg (a)</strong>

</dt>

<dd>

Return the logical negation of the arguments.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

not <em>a</em>

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">--&gt; {true, false, false, false}

</span>functional.<span class="function-name">bind</span> (functional.map, {std.ielems, neg}) {<span class="keyword">false</span>, <span class="keyword">true</span>, <span class="number">1</span>, <span class="number">0</span>}</pre>

</ul>

<dt>

<a name = "neq"></a>

<strong>neq (a, b)</strong>

</dt>

<dd>

Return the inequality of the arguments.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

<code>false</code> if <em>a</em> is <em>b</em>, otherwise <code>true</code>

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">--&gt; true

</span><span class="keyword">local</span> f = <span class="global">require</span> <span class="string">"std.functional"</span>

<span class="global">table</span>.<span class="function-name">empty</span> (f.<span class="function-name">filter</span> (f.<span class="function-name">bind</span> (neq, {<span class="number">6</span>}), std.ielems, {<span class="number">6</span>, <span class="number">6</span>, <span class="number">6</span>})</pre>

</ul>

<dt>

<a name = "pow"></a>

<strong>pow (a, b)</strong>

</dt>

<dd>

Return the exponent of the arguments.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

the <em>a</em> to the power of <em>b</em>

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">--&gt; 4096

</span>functional.<span class="function-name">foldl</span> (pow, {<span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>})</pre>

</ul>

<dt>

<a name = "prod"></a>

<strong>prod (a, b)</strong>

</dt>

<dd>

Return the product of the arguments.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

the product of <em>a</em> and <em>b</em>

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">--&gt; 10000000

</span>functional.<span class="function-name">foldl</span> (prod, {<span class="number">10000</span>, <span class="number">100</span>, <span class="number">10</span>})</pre>

</ul>

<dt>

<a name = "quot"></a>

<strong>quot (a, b)</strong>

</dt>

<dd>

Return the quotient of the arguments.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

the quotient <em>a</em> and <em>b</em>

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">--&gt; 1000

</span>functional.<span class="function-name">foldr</span> (quot, {<span class="number">10000</span>, <span class="number">100</span>, <span class="number">10</span>})</pre>

</ul>

<dt>

<a name = "set"></a>

<strong>set (t, k, v)</strong>

</dt>

<dd>

Set a table element, honoring metamethods.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">t</span>

<span class="types"><a class="type" href="https://www.lua.org/manual/5.1/manual.html#5.5">table</a></span>

a table

</li>

<li><span class="parameter">k</span>

a key to lookup in <em>t</em>

</li>

<li><span class="parameter">v</span>

a value to set for <em>k</em>

</li>

</ul>

<h3>Returns:</h3>

<ol>

<span class="types"><a class="type" href="https://www.lua.org/manual/5.1/manual.html#5.5">table</a></span>

<em>t</em>

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">-- destructive table merge:

</span><span class="comment">--&gt; {"one", bar="baz", two=5}

</span>functional.<span class="function-name">reduce</span> (set, {<span class="string">"foo"</span>, bar=<span class="string">"baz"</span>}, {<span class="string">"one"</span>, two=<span class="number">5</span>})</pre>

</ul>

<dt>

<a name = "sum"></a>

<strong>sum (a, b)</strong>

</dt>

<dd>

Return the sum of the arguments.

<h3>Parameters:</h3>

<ul>

<li><span class="parameter">a</span>

an argument

</li>

<li><span class="parameter">b</span>

another argument

</li>

</ul>

<h3>Returns:</h3>

<ol>

the sum of the <em>a</em> and <em>b</em>

</ol>

<h3>Usage:</h3>

<ul>

<pre class="example"><span class="comment">--&gt; 10110

</span>functional.<span class="function-name">foldl</span> (sum, {<span class="number">10000</span>, <span class="number">100</span>, <span class="number">10</span>})</pre>

</ul>

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