#13735: RankNTypes don't work with PatternSynonyms -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: invalid | Keywords: | PatternSynonyms Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Iceland_jack): There is where my intuition breaks down. Writing this works, so higher- rank types + pattern synonyms are fine {{{#!hs newtype A = A (forall xx. xx -> xx) pattern PatA :: (forall xx. xx -> xx) -> A pattern PatA a = A a a :: A -> A a (PatA f) = A f }}} but I don't understand why this is different {{{#!hs newtype Endo a = Endo (a -> a) newtype B = B (forall xx. Endo xx) pattern PatB :: (a -> a) -> PatB pattern PatB f <- B (Endo f) b :: B -> forall xx. xx -> xx b (B (Endo f)) = f }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13735#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler