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{-# LANGUAGE RankNTypes #-}
-- A test for rank-3 types
module ShouldCompile where
data Fork a = ForkC a a
mapFork :: forall a1 a2 . (a1 -> a2) -> (Fork a1 -> Fork a2)
mapFork mapA (ForkC a1 a2) = ForkC (mapA a1) (mapA a2)
data SequF s a = EmptyF | ZeroF (s (Fork a)) | OneF a (s (Fork a))
newtype HFix h a = HIn (h (HFix h) a)
type Sequ = HFix SequF
mapSequF :: forall s1 s2 . (forall b1 b2 . (b1 -> b2) -> (s1 b1 -> s2 b2))
-> (forall a1 a2 . (a1 -> a2) -> (SequF s1 a1 -> SequF s2 a2))
mapSequF mapS mapA EmptyF = EmptyF
mapSequF mapS mapA (ZeroF as) = ZeroF (mapS (mapFork mapA) as)
mapSequF mapS mapA (OneF a as)= OneF (mapA a) (mapS (mapFork mapA) as)
mapHFix :: forall h1 h2 . (forall f1 f2 . (forall c1 c2 . (c1 -> c2) -> (f1 c1 -> f2 c2))
-> (forall b1 b2 . (b1 -> b2) -> (h1 f1 b1 -> h2 f2 b2)))
-> (forall a1 a2 . (a1 -> a2) -> (HFix h1 a1 -> HFix h2 a2))
mapHFix mapH mapA (HIn v) = HIn (mapH (mapHFix mapH) mapA v)
mapSequ :: forall a1 a2 . (a1 -> a2) -> (Sequ a1 -> Sequ a2)
mapSequ = mapHFix mapSequF
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