#12089: :kind command allows unsaturated type family, -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs data A = B type family F a where F B = String infixr 9 `Compose` class (f (g x)) => (f `Compose` g) x instance (f (g x)) => (f `Compose` g) x }}} GHCi accepts {{{ ghci> :kind Compose Eq F Compose Eq F :: A -> Constraint }}} but when used in code it gets rejected {{{ -- tvI6.hs:13:8-33: error: … -- • The type family ‘F’ should have 1 argument, but has been given none -- • In the type signature: -- foo :: (Eq `Compose` F) a => String -- Compilation failed. foo :: (Eq`Compose`F) a => String foo = undefined }}} Bug? Version 8.0.0.20160511 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12089 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler