ased tests of these laws for new modules satisfying this interface.</p><dl><dt>parameter M</dt><dd><p>An implementation of <a href="../module-type-S/index.html"><span>Monoid</span></a></p></dd></dl></header><h3 class="heading">Parameters</h3><ul><li><code><a href="argument-1-M/index.html">M</a> : <a href="../index.html#module-type-S">S</a></code></li></ul><h3 class="heading">Signature</h3><dl><dt class="spec value" id="val-associativity"><a href="#val-associativity" class="anchor"></a><code><span class="key