{-# htermination (compareMyInt :: MyInt -> MyInt -> Ordering) #-} import qualified Prelude data MyBool = MyTrue | MyFalse data List a = Cons a (List a) | Nil data MyInt = Pos Nat | Neg Nat ; data Nat = Succ Nat | Zero ; data Ordering = LT | EQ | GT ; primCmpNat :: Nat -> Nat -> Ordering; primCmpNat Zero Zero = EQ; primCmpNat Zero (Succ y) = LT; primCmpNat (Succ x) Zero = GT; primCmpNat (Succ x) (Succ y) = primCmpNat x y; primCmpInt :: MyInt -> MyInt -> Ordering; primCmpInt (Pos Zero) (Pos Zero) = EQ; primCmpInt (Pos Zero) (Neg Zero) = EQ; primCmpInt (Neg Zero) (Pos Zero) = EQ; primCmpInt (Neg Zero) (Neg Zero) = EQ; primCmpInt (Pos x) (Pos y) = primCmpNat x y; primCmpInt (Pos x) (Neg y) = GT; primCmpInt (Neg x) (Pos y) = LT; primCmpInt (Neg x) (Neg y) = primCmpNat y x; compareMyInt :: MyInt -> MyInt -> Ordering compareMyInt = primCmpInt;