an>) <span>&#45;&gt;</span> <span class="keyword">sig</span> ... <span class="keyword">end</span></code></div><div class="spec module" id="module-Heyting_Algebra"><a href="#module-Heyting_Algebra" class="anchor"></a><code><span class="keyword">module</span> <a href="Heyting_Algebra/index.html">Heyting_Algebra</a> : <span class="keyword">functor</span> (<a href="Heyting_Algebra/argument-1-HA/index.html">HA</a> : <a href="../../../Bastet/Interface/index.html#module-type-HEYTING_ALGEBRA">Bastet.Interface.HEYTI