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{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE FlexibleContexts #-}
module Instances where
class Foo f where
foo :: f Int -> a -> f a
foo' :: f (f a) -> Int -> f (f Int)
foo = undefined
foo' = undefined
instance Foo Maybe
instance Foo []
instance (Eq a, Foo f) => Foo ((,) (f a))
instance Foo (Either a)
instance Foo ((,,) a a)
class Foo f => Bar f a where
bar :: f a -> f Bool -> a
bar' :: f (f a) -> f (f (f b))
bar = undefined
bar' = undefined
instance Bar Maybe Bool
instance Bar Maybe [a]
instance Bar [] (a, a)
instance Foo f => Bar (Either a) (f a)
instance Foo ((,,) a b) => Bar ((,,) a b) (a, b, a)
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