="val-join_all"><a href="#val-join_all" class="anchor"></a><code><span><span class="keyword">val</span> join_all : <span><span><a href="Domain/index.html#type-t">Domain.t</a> list</span> <span class="arrow">&#45;&gt;</span></span> <span><span class="label">into</span>:<span><a href="Domain/index.html#type-t">Domain.t</a> option</span> <span class="arrow">&#45;&gt;</span></span> <span><a href="Domain/index.html#type-t">Domain.t</a> option</span></span></code></div><div class="spec-doc"><p>Joins the abstract 