o it keeps the order of both lists and has no duplicates.</p></dd></dl><dl><dt class="spec value" id="val-merge_dedup"><a href="#val-merge_dedup" class="anchor"></a><code><span class="keyword">val</span> merge_dedup : <span><span class="type-var">'a</span> list</span> <span>&#45;&gt;</span> <span><span class="type-var">'a</span> list</span> <span>&#45;&gt;</span> <span>compare:<span>(<span class="type-var">'a</span> <span>&#45;&gt;</span> <span class="type-var">'a</span> <span>&#45;&gt;</span> int)</span></