an> list</span> <span>&#45;&gt;</span> <span><span class="type-var">'a</span> list</span> * <span><span class="type-var">'a</span> list</span></code></dt><dt class="spec value" id="val-assoc"><a href="#val-assoc" class="anchor"></a><code><span class="keyword">val</span> assoc : <span class="type-var">'a</span> <span>&#45;&gt;</span> <span><span>(<span class="type-var">'a</span> * <span class="type-var">'b</span>)</span> list</span> <span>&#45;&gt;</span> <span class="type-var">'b</span></code></dt><dt class