tion</span> <span>&#45;&gt;</span> <span><span class="type-var">'b</span> option</span> <span>&#45;&gt;</span> <span><span>(<span class="type-var">'a</span> * <span class="type-var">'b</span>)</span> option</span></code></dt><dd><p>merge on options</p></dd></dl><dl><dt class="spec value" id="val-join_bot2"><a href="#val-join_bot2" class="anchor"></a><code><span class="keyword">val</span> join_bot2 : <span>(<span class="type-var">'a</span> <span>&#45;&gt;</span> <span class="type-var">'a</span> <span>&#45;&g