longest sub-list).<br>
</div>
<pre><span id="VALflatten"><span class="keyword">val</span> flatten</span> : <code class="type">'a list list -&gt; 'a list</code></pre><div class="info">
Same as <code class="code">concat</code>.  Not tail-recursive
   (length of the argument + length of the longest sub-list).<br>
</div>
<br>
<span id="6_Iterators"><h6>Iterators</h6></span><br>
<pre><span id="VALiter"><span class="keyword">val</span> iter</span> : <code class="type">('a -&gt; unit) -&gt; 'a list -&gt; unit</cod