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module Identity where
import Test.QuickCheck
import Test.QuickCheck.Checkers
newtype Identity a = Identity a
deriving (Eq, Ord, Show)
instance Functor Identity where
fmap f (Identity x) = Identity $ f x
instance Applicative Identity where
pure = Identity
(Identity f) <*> x = fmap f x
instance Monad Identity where
return = pure
(Identity x) >>= f = f x
instance Arbitrary a => Arbitrary (Identity a) where
arbitrary = fmap Identity $ arbitrary
instance Eq a => EqProp (Identity a) where
(=-=) = eq
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