<span class="arrow">&#45;&gt;</span></span> <span><span><span class="type-var">'a</span> option</span> <span class="arrow">&#45;&gt;</span></span> <span class="type-var">'a</span></span></code></div><div class="spec-doc"><p>Like <code>Option.value ~default:(f ())</code> but <code>f</code> is called only if <code>None</code>.</p></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-if_none_evalopt"><a href="#val-if_none_evalopt" class="anchor"></a><code><span><span class="keyword">val</