"type-compare">compare()</a></h3>
<p><tt>compare(A, B) = fun((A, B) -&gt; boolean())</tt></p>


<h3 class="typedecl"><a name="type-filtermap">filtermap()</a></h3>
<p><tt>filtermap(A, B) = fun((A) -&gt; boolean() | {true, B})</tt></p>


<h3 class="typedecl"><a name="type-fold">fold()</a></h3>
<p><tt>fold(Elem, AccIn, AccOut) = fun((Elem, AccIn) -&gt; AccOut)</tt></p>


<h3 class="typedecl"><a name="type-iterator">iterator()</a></h3>
<p><b>abstract datatype</b>: <tt>iterator(Over)</tt></p>


<h3 class="typede