doc-src/IsarAdvanced/Codegen/Thy/examples/bool2.ML

(continued)

structure ROOT = 
struct

structure HOL = 
struct

fun nota false = true
  | nota true = false;

end; (*struct HOL*)

structure Nat = 
struct

datatype nat = Zero_nat | Suc of nat;

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

fun less_eq_nat m n = HOL.nota (less_nat n m);

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*)

end; (*struct ROOT*)