t; 'b option</code></pre><div class="info ">
<div class="info-desc">
<p>Same as <a href="List.html#VALassoc_opt"><code class="code"><span class="constructor">List</span>.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><span id="VALmem_assoc"><span class="keyword">val</span> mem_assoc</span> : <code class="type">'a -&gt; map:('a * 'b) list -&gt; bool</code></pre><div cla