option</span> <span class="arrow">&#45;&gt;</span></span> <span class="type-var">'a</span></span></code></div><div class="spec-doc"><p><code>if_none_eval ~f x</code> evaluates to <code>y</code> if <code>x=Some y</code> else to <code>f ()</code>. Useful for terminating chains built with <code>if_none_evalopt</code>. This is exactly the same as <code>value_default_f</code> but with a better name.</p></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-exists2"><a href="#val-exists2" cla