#7916: PolyKinds without type signatures ----------------------------------------+----------------------------------- Reporter: monoidal | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler (Type checker) | Version: 7.7 Resolution: fixed | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: GHC rejects valid program | Difficulty: Unknown Testcase: polykinds/T7916 | Blockedby: Blocking: | Related: ----------------------------------------+----------------------------------- Comment(by monoidal): Thank you for fixing it! I appreciate it. Maybe I'm doing something wrong, but the regression test does not seem to capture the bug - it compiles before and after the fix. Here's one possibility to test that g is really polymorphic: {{{ {-# LANGUAGE PolyKinds, ExplicitForAll #-} module T7916 where f :: forall (m :: k -> *) (a :: k). m a -> m a f = id g = f data M f = M (f Int) -- Test that g :: forall (m :: k -> *) (a :: k). m a -> m a g1 = g :: [Int] -> [Int] g2 = g :: M [] -> M [] }}} Both g1 and g2 are needed to detect the behaviour before the fix. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7916#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler