te max permitted integeger</p><pre><code class="ml">let validator input =
  let open Validator in
  build build_valid
  |&gt; validate input.age (int_max 6 &quot;Must be 6 or younger&quot;)</code></pre></dd></dl><dl><dt class="spec value" id="val-list_is_not_empty"><a href="#val-list_is_not_empty" class="anchor"></a><code><span class="keyword">val</span> list_is_not_empty : <span><span>(<span><span class="type-var">'a</span> list</span>, <span><span class="type-var">'a</span> list</span>, <span class="typ