OID">Bastet.Interface.MONOID</a></code></li></ul><h3 class="heading">Signature</h3><dl><dt class="spec value" id="val-fold_map"><a href="#val-fold_map" class="anchor"></a><code><span class="keyword">val</span> fold_map : <span>(<span class="type-var">'a</span> <span>&#45;&gt;</span> <a href="argument-1-M/index.html#type-t">M.t</a>)</span> <span>&#45;&gt;</span> <span><span class="type-var">'a</span> <a href="../index.html#type-t">t</a></span> <span>&#45;&gt;</span> <a href="argument-1-M/index.html#type-t">M