anchored" id="val-exists"><a href="#val-exists" class="anchor"></a><code><span><span class="keyword">val</span> exists : <span><a href="#type-t">t</a> <span class="arrow">&#45;&gt;</span></span> <span><span class="label">f</span>:<span>(<span><a href="../PulseValueHistory/index.html#type-event">ValueHistory.event</a> <span class="arrow">&#45;&gt;</span></span> bool)</span> <span class="arrow">&#45;&gt;</span></span> bool</span></code></div><div class="spec-doc"><p>whether the trace contains an event satisfy