{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE ScopedTypeVariables #-}
#if HAVE_QUANTIFIED_CONSTRAINTS
{-# LANGUAGE QuantifiedConstraints #-}
#endif
{-# OPTIONS_GHC -Wall #-}
module Test.QuickCheck.Classes.Contravariant
(
#if HAVE_UNARY_LAWS
contravariantLaws
#endif
) where
import Data.Functor.Contravariant
import Test.QuickCheck hiding ((.&.))
#if HAVE_UNARY_LAWS
import Test.QuickCheck.Arbitrary (Arbitrary1(..))
import Data.Functor.Classes (Eq1,Show1)
#endif
import Test.QuickCheck.Property (Property)
import Test.QuickCheck.Classes.Common
#if HAVE_UNARY_LAWS
import Test.QuickCheck.Classes.Compat (eq1)
#endif
#if HAVE_UNARY_LAWS
contravariantLaws ::
#if HAVE_QUANTIFIED_CONSTRAINTS
(Contravariant f, forall a. Eq a => Eq (f a), forall a. Show a => Show (f a), forall a. Arbitrary a => Arbitrary (f a))
#else
(Contravariant f, Eq1 f, Show1 f, Arbitrary1 f)
#endif
=> proxy f
-> Laws
contravariantLaws p = Laws "Contravariant"
[ ("Identity", contravariantIdentity p)
, ("Composition", contravariantComposition p)
]
contravariantIdentity :: forall proxy f.
#if HAVE_QUANTIFIED_CONSTRAINTS
(Contravariant f, forall a. Eq a => Eq (f a), forall a. Show a => Show (f a), forall a. Arbitrary a => Arbitrary (f a))
#else
(Contravariant f, Eq1 f, Show1 f, Arbitrary1 f)
#endif
=> proxy f -> Property
contravariantIdentity _ = property $ \(Apply (a :: f Integer)) -> eq1 (contramap id a) a
contravariantComposition :: forall proxy f.
#if HAVE_QUANTIFIED_CONSTRAINTS
(Contravariant f, forall a. Eq a => Eq (f a), forall a. Show a => Show (f a), forall a. Arbitrary a => Arbitrary (f a))
#else
(Contravariant f, Eq1 f, Show1 f, Arbitrary1 f)
#endif
=> proxy f -> Property
contravariantComposition _ = property $ \(Apply (a :: f Integer)) (f' :: QuadraticEquation) (g' :: QuadraticEquation) -> do
let f = runQuadraticEquation f'
g = runQuadraticEquation g'
eq1 (contramap f (contramap g a)) (contramap (g . f) a)
#endif