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{-# LANGUAGE Rank2Types #-}
-- !!! Check that record selectors for polymorphic fields work right
module Main where
class Foo a where
bar :: a -> [a]
instance Foo Int where
bar x = replicate x x
instance Foo Bool where
bar x = [x, not x]
data Record = R {
blub :: forall a. Foo a => a -> [a]
}
main = do { let r = R {blub = bar}
; print (blub r (3::Int))
; print (blub r True)
}
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