The following shows the use of lists and matching. */</span></i>

<b><span style='color:#000000;'>let</span></b> filter = \f \lst {
   <b><span style='color:#000000;'>match</span></b> lst <b><span style='color:#000000;'>with</span></b>
   | <span style='color:#006e28;'>%h</span> :: <span style='color:#006e28;'>%t</span> <b><span style='color:#000000;'>when</span></b> f h -&gt; h :: filter f t
   | <span style='color:#006e28;'>%_</span> :: <span style='color:#006e28;'>%t</span> -&gt; filter f t
   | [] -&gt;