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{-# LANGUAGE RankNTypes #-}
module Bug where
data T a = MkT
out :: forall a. T a -> ()
out MkT = ()
inHoisted :: forall r. () -> (forall a. T a -> r) -> r
inHoisted _ foo = foo MkT
inUnhoisted :: () -> forall r. (forall a. T a -> r) -> r
inUnhoisted _ foo = foo MkT
testHoisted :: ()
testHoisted = inHoisted () out
testUnhoisted :: ()
testUnhoisted = inUnhoisted () out
----------------
data A s = A { unA :: () }
runA1 :: (forall s. A s) -> ()
runA1 a = unA a
-- doesn't work :(
runA2 :: (forall s. A s) -> ()
runA2 (A a) = a
runA3 :: (forall s. A s) -> ()
runA3 a = case a of A x -> x
runA4 :: (forall s. A s) -> ()
runA4 a = let A x = a in x
runA5 :: (forall s. A s) -> ()
runA5 a = go a
where go (A a) = a
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