code>sub</code> according to whether domain identifiers satisfy <code>filter</code>.</p></div></div><div class="odoc-spec"><div class="spec value" id="val-sub_domain" class="anchored"><a href="#val-sub_domain" class="anchor"></a><code><span><span class="keyword">val</span> sub_domain : <span><a href="#type-subst">subst</a> <span class="arrow">&#45;&gt;</span></span> <span><a href="../../IR/Ident/index.html#type-t">IR.Ident.t</a> list</span></span></code></div><div class="spec-doc"><p>Return the list of iden