a</span>, float)</span> Stdlib.result</span></code></dt></dl><dl><dt class="spec value" id="val-fold_left"><a href="#val-fold_left" class="anchor"></a><code><span class="keyword">val</span> fold_left : <span>(<span class="type-var">'a</span> <span>&#45;&gt;</span> <span class="type-var">'b</span> <span>&#45;&gt;</span> <span class="type-var">'a</span>)</span> <span>&#45;&gt;</span> <span class="type-var">'a</span> <span>&#45;&gt;</span> <span><span class="type-var">'b</span> <a href="index.html#type-t">t</