doc-src/IsarAdvanced/Codegen/Thy/examples/fac_case.ML
author berghofe
Thu, 03 Jul 2008 00:56:45 +0200
changeset 27450 d45d2850aaed
parent 25160 72fcf0832cfe
permissions -rw-r--r--
Replaced all but one occurrence of perm_simp_tac by perm_simproc_app, since perm_simp_tac now behaves in a different way (due to changes in swap_simps).

structure Nat = 
struct

datatype nat = Suc of nat | Zero_nat;

val one_nat : nat = Suc Zero_nat;

fun nat_case f1 f2 Zero_nat = f1
  | nat_case f1 f2 (Suc nat) = f2 nat;

fun plus_nat (Suc m) n = plus_nat m (Suc n)
  | plus_nat Zero_nat n = n;

fun times_nat (Suc m) n = plus_nat n (times_nat m n)
  | times_nat Zero_nat n = Zero_nat;

end; (*struct Nat*)

structure Codegen = 
struct

fun fac n =
  (case n of Nat.Zero_nat => Nat.one_nat
     | Nat.Suc m => Nat.times_nat n (fac m));

end; (*struct Codegen*)