doc-src/TutorialI/Misc/fakenat.thy

named the primrec clauses of upt

(*<*)
theory fakenat = Main:;
(*>*)

text{*\noindent
The type \isaindexbold{nat} of natural numbers is predefined and
behaves like
*}

datatype nat = "0" | Suc nat
(*<*)
end
(*>*)