span>&#45;&gt;</span> <span><a href="index.html#type-t">t</a> option</span></code></dt><dt class="spec value" id="val-log"><a href="#val-log" class="anchor"></a><code><span class="keyword">val</span> log : <a href="index.html#type-t">t</a> <span>&#45;&gt;</span> <span><a href="index.html#type-t">t</a> option</span></code></dt><dt class="spec value" id="val-eval_fun"><a href="#val-eval_fun" class="anchor"></a><code><span class="keyword">val</span> eval_fun : string <span>&#45;&gt;</span> <span><a href="index