#10524: PolyKinds doesn't interact well with DeriveFunctor -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: #10561 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Yes, but test `deriving/should_compile/T10561` still fails: {{{ newtype Compose f g a = Compose (f (g a)) deriving Functor }}} (with `-XPolyKinds`) produces {{{ T10561.hs:10:52: error: • Couldn't match kind ‘k’ with ‘*’ arising from the first field of ‘Compose’ (type ‘f (g a)’) • When deriving the instance for (Functor (Compose f g)) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10524#comment:15 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler