href="List.html#VALrev"><code class="code"><span class="constructor">List</span>.rev</code></a><code class="code">&nbsp;(</code><a href="List.html#VALmap"><code class="code"><span class="constructor">List</span>.map</code></a><code class="code">&nbsp;f&nbsp;l)</code>, but is tail-recursive and
   more efficient.</p>
</div>
</div>

<pre><span id="VALfold_left"><span class="keyword">val</span> fold_left</span> : <code class="type">f:('a -&gt; 'b -&gt; 'a) -&gt; init:'a -&gt; 'b list -&gt; 'a</code></pre><div 