<span class="keyword">val</span> unit : <a href="index.html#type-t">t</a></code></dt><dd><p><code>unit</code> is the identity element in the monoid over <a href="index.html#type-t"><code>t</code></a>.</p><p>Every implementation must ensure that for any <code>x : t</code>, <a href="index.html#val-unit"><code>unit</code></a> is the identity element under <a href="index.html#val-op"><code>op</code></a>, thus that the equation <code>(x * unit) =
      (unit * x) = x</code> holds.</p></dd></dl></div></body></htm