structure HOL =
struct
datatype boola = False | True;
fun anda x True = x
| anda x False = False
| anda True x = x
| anda False x = False;
end; (*struct HOL*)
structure Nat =
struct
datatype nat = Suc of nat | Zero_nat;
fun less_nat n (Suc m) = less_eq_nat n m
| less_nat n Zero_nat = HOL.False
and less_eq_nat (Suc n) m = less_nat n m
| less_eq_nat Zero_nat m = HOL.True;
end; (*struct Nat*)
structure Codegen =
struct
fun in_interval (k, l) n =
HOL.anda (Nat.less_eq_nat k n) (Nat.less_eq_nat n l);
end; (*struct Codegen*)