#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: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by RyanGlScott): It appears that since {{{f :: k -> *}}} and {{{g :: * -> k}}} in 7.10's {{{Functor}}} instance, and since the kind of {{{Compose}}} is {{{(k -> *) -> (k1 -> k) -> k1 -> *}}}, it would follow that {{{Compose f g}}} is of kind {{{* -> *}}} (unless I'm reading that wrong). I raised this issue since at the moment, 7.10 can handle certain poly- kinded derived {{{Functor}}} instances (e.g., {{{newtype Alt f a = Alt (f a) deriving Functor}}}), but throwing more than one poly-kinded type constructor into the mix causes things to go haywire. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10524#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler