ode>W = typ</code>;
an implicit <code>mapper</code> is used, which also allows calculation of the type <code>RecType</code>.
</p></div><dl class="paramcmts block"><dt class="tparam">RecType</dt><dd class="cmt"><p>type of the <code>rec</code> function returned;</p></dd><dt class="tparam">InducType</dt><dd class="cmt"><p>not used here, but part of the definition of the <code>mapper</code>.</p></dd><dt class="param">X</dt><dd class="cmt"><p>the codomain to which we wish to define recursive functions - the only