#7939: RHS of associated type not kind-checked ------------------------------------------+--------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.7 Resolution: | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: GHC accepts invalid program | Difficulty: Unknown Testcase: ghci/scripts/T7939 | Blockedby: Blocking: | Related: ------------------------------------------+--------------------------------- Changes (by monoidal): * owner: goldfire => * status: closed => new * resolution: fixed => Comment: Something is suspicious here. GHC accepts original program {{{ {-# LANGUAGE TypeFamilies, PolyKinds #-} class Foo a where type Bar a instance Foo Int where type Bar Int = Maybe instance Foo Bool where type Bar Bool = Double }}} but rejects {{{ {-# LANGUAGE TypeFamilies, PolyKinds #-} type family Baz a type instance Baz Int = Maybe type instance Baz Bool = Double }}} Is this really expected? Even more, you can write {{{ instance Foo Bool where type Bar Bool = Double type Bar Bool = Maybe }}} -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7939#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler