* Pure/library.ML: several combinators for linear functional transformations;
* Pure/library.ML: canonical list combinators fold, fold_rev, and fold_yield;
* Pure/term.ML: combinators fold_atyps, fold_aterms, fold_term_types, fold_types;
(*<*)
theory Plus imports Main begin
(*>*)
text{*\noindent Define the following addition function *}
consts plus :: "nat \<Rightarrow> nat \<Rightarrow> nat"
primrec
"plus m 0 = m"
"plus m (Suc n) = plus (Suc m) n"
text{*\noindent and prove*}
(*<*)
lemma [simp]: "!m. plus m n = m+n"
apply(induct_tac n)
by(auto)
(*>*)
lemma "plus m n = m+n"
(*<*)
by(simp)
end
(*>*)