foldr is a good consumer (but not necessarily a good producer)
<function>++</function>
</para>
</listitem>
-<listitem>
+<listitem>
<para>
<function>map</function>
</para>
</listitem>
-<listitem>
+<listitem>
<para>
<function>filter</function>
</para>
<function>++</function> (on its first argument)
</para>
</listitem>
+
<listitem>
+<para>
+ <function>foldr</function>
+</para>
+</listitem>
+<listitem>
<para>
<function>map</function>
</para>