t;</span> <span><span>(string, string, <span class="type-var">'err</span>)</span> <a href="index.html#type-validator_builder">validator_builder</a></span></code></dt><dd><p>Validate the min length of a string</p><pre><code class="ml">let validator input =
  let open Validator in
  build build_valid
  |&gt; validate input.password (string_has_min_length 3 &quot;Min 3 chars&quot;)</code></pre></dd></dl><dl><dt class="spec value" id="val-string_has_max_length"><a href="#val-string_has_max_length" class="anch