an>init:<span class="type-var">'accum</span> <span class="arrow">&#45;&gt;</span></span> <span>f:<span>( <span><span class="type-var">'accum</span> <span class="arrow">&#45;&gt;</span></span> <span><a href="#type-elt">elt</a> <span class="arrow">&#45;&gt;</span></span> <span class="type-var">'accum</span> )</span> <span class="arrow">&#45;&gt;</span></span> <span class="type-var">'accum</span></span></code></div></div><div class="odoc-spec"><div class="spec value" id="val-fold_map" class="anchored"><a href=