#8055: ghc: panic! (the 'impossible' happened) [..] kindFunResult ---------------------------------+---------------------------------- Reporter: guest | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Resolution: duplicate | Keywords: Operating System: MacOS X | Architecture: x86_64 (amd64) Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: ---------------------------------+---------------------------------- Changes (by thoughtpolice): * status: new => closed * resolution: => duplicate Comment: Thanks. This is correctly rejected in HEAD: {{{ Prelude> :m +Data.Either Control.Applicative Control.Monad.Trans Prelude Data.Either Control.Applicative Control.Monad.Trans> :t either error id <$> lift <interactive>:1:21: Kind incompatibility when matching types: t0 :: (* -> *) -> * -> * Either :: * -> * -> * Expected type: m a -> Either [Char] a Actual type: m a -> t0 m a In the second argument of ‛(<$>)’, namely ‛lift’ In the expression: either error id <$> lift }}} See also: #7927, #7920, #7905, #7696, and #7513 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8055#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler