dest_ctyp: raise exception for non-constructor;
dest_comb: replaced expensive fastype_of by Term.argument_type;
dest_abs: replaced expensive variant_abs by Term.dest_abs;
hyps: fast_term_ord;
(*<*)
theory fakenat imports Main begin;
(*>*)
text{*\noindent
The type \tydx{nat} of natural
numbers is predefined to have the constructors \cdx{0} and~\cdx{Suc}. It behaves as if it were declared like this:
*}
datatype nat = 0 | Suc nat
(*<*)
end
(*>*)