doc-src/IsarAdvanced/Codegen/Thy/examples/bool_mlbool.ML

Reintroduce set_interpreter for Collect and op :.
I removed them by accident when removing old code that dealt with the "set" type.
Incidentally, there is still some broken "set" code in Refute that should be fixed (see TODO in refute.ML).

structure Nat = 
struct

datatype nat = Suc of nat | Zero_nat;

fun less_nat m (Suc n) = less_eq_nat m n
  | less_nat n Zero_nat = false
and less_eq_nat (Suc m) n = less_nat m n
  | less_eq_nat Zero_nat n = true;

end; (*struct Nat*)

structure Codegen = 
struct

fun in_interval (k, l) n =
  (Nat.less_eq_nat k n) andalso (Nat.less_eq_nat n l);

end; (*struct Codegen*)