#8531: ghc crash from kinds -----------------------------------+--------------------------------------- Reporter: guest | Owner: Type: bug | Status: new Priority: lowest | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: MacOS X Architecture: | Type of failure: Compile-time crash Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | -----------------------------------+--------------------------------------- When I run this in ghci: {{{ let x :: MaybeT IO (Ptr Int); x = (lift newCString "hi") >>= nullableToMaybeT }}} I get this output: {{{ Couldn't match kind `* -> *' with `*' Expected type: [Char] -> MaybeT IO (Ptr Int) Actual type: [Char] -> MaybeT IO (Ptr Int) Kind incompatibility when matching types: [Char] :: * -> * [Char] :: * The function `lift'ghc: panic! (the 'impossible' happened) (GHC version 7.6.3 for x86_64-apple-darwin): kindFunResult <<details unavailable>> }}} where nullToMaybeT is: {{{ nullableToMaybeT :: Monad m => Ptr a -> MaybeT m (Ptr a) nullableToMaybeT ptr = do case (ptr == nullPtr) of True -> (MaybeT . return) Nothing False -> return ptr }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8531 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler