><code class="code">List.assoc_opt</code></a>, but uses physical equality instead of
   structural equality to compare keys.</p>
</div>
<ul class="info-attributes">
<li><b>Since</b> 4.05.0</li>
</ul>
</div>

<pre id="VALmem_assoc">val mem_assoc : 'a -&gt; ('a * 'b) list -&gt; bool</pre><div class="info ">
<div class="info-desc">
<p>Same as <a href="List.html#VALassoc"><code class="code">List.assoc</code></a>, but simply return <code class="code">true</code> if a binding exists,
   and <code class="code">fal