t;</span> <span class="type-var">'a</span>)</span> <span>&#45;&gt;</span> <span><span class="type-var">'a</span> option</span> <span>&#45;&gt;</span> <span><span class="type-var">'a</span> option</span> <span>&#45;&gt;</span> <span><span class="type-var">'a</span> option</span></code></dt><dd><p>join on options</p></dd></dl><dl><dt class="spec module" id="module-VarMap"><a href="#module-VarMap" class="anchor"></a><code><span class="keyword">module</span> <a href="VarMap/index.html">VarMap</a> : <span class=