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{-# LANGUAGE GADTs #-}
module T3950 where
-- Id :: (* -> * -> *) -> * -> * -> *
data Id p x y = Id (p x y)
-- Sealed :: (* -> *) -> *
data Sealed p where
Sealed :: p x -> Sealed p
-- w :: (* -> * -> *) -> *
-- Id p :: * -> * -> *
rp :: Bool -> Maybe (w (Id p))
rp _ = Just rp'
where rp' :: Sealed (Id p x)
rp' = undefined
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