><code><span><span class="keyword">val</span> fold_map : <span><a href="#type-t">t</a> <span class="arrow">&#45;&gt;</span></span> <span>init:<span class="type-var">'a</span> <span class="arrow">&#45;&gt;</span></span> <span>f:<span>(<span><span class="type-var">'a</span> <span class="arrow">&#45;&gt;</span></span> <span><a href="#type-value">value</a> <span class="arrow">&#45;&gt;</span></span> <span class="type-var">'a</span> * <a href="#type-value">value</a>)</span> <span class="arrow">&#45;&gt;</span></