.html#type-t">t</a> <span>&#45;&gt;</span> <a href="index.html#type-t">t</a></code></dt><dt class="spec value" id="val-fold"><a href="#val-fold" class="anchor"></a><code><span class="keyword">val</span> fold : <span>(<a href="index.html#type-elt">elt</a> <span>&#45;&gt;</span> <span class="type-var">'a</span> <span>&#45;&gt;</span> <span class="type-var">'a</span>)</span> <span>&#45;&gt;</span> <a href="index.html#type-t">t</a> <span>&#45;&gt;</span> <span class="type-var">'a</span> <span>&#45;&gt;</span> <