-is_not" class="anchored"><a href="#val-is_not" class="anchor"></a><code><span><span class="keyword">val</span> is_not : <span><span><span class="type-var">'a</span> <a href="#type-t">t</a></span> <span class="arrow">&#45;&gt;</span></span> <span>bool <a href="#type-t">t</a></span></span></code></div><div class="spec-doc"><p><code>is_not p</code> parses value <code>true</code> if <code>p</code> fails to parse and <code>false</code> otherwise. <b>Note</b> evaluating <code>p</code> doesn't consume any input.<