#12553: Reference kind in a type instance declaration defined in another instance declaration -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Richard says
but `Internal` looks OK to me. It should be accepted.
Alas Jack has posted no fewer than four different declarations of `Internal`, so I'm not sure which one(s) you think should be accepted. Jack, what kind do you WANT `Internal` to have? For example, in the one that works: {{{ type family Domain a :: Sig u -> Type type family Internal (a :: Type) :: k }}} I believe we get {{{ Domain :: forall (u :: Type). Type -> Sig u -> Type Internal :: forall (k :: Type). Type -> k }}} Now when writing them in associated form we have {{{ class Syntactic a where type Domain a :: Sig u -> Type type Internal a :: u }}} and this should not really be different. I think it shoudl be accepted. But I do have a question: should we get {{{ Domain :: Type -> forall u. Sig u -> Type or Domain :: forall u. Type -> Sig u -> Type }}} and does it matter at use sites? Richard The same question arises with class methods. Given {{{ class C a where op :: forall b. Ord b => b -> a -> a }}} do we get {{{ op :: forall a. C a => forall b. Ord b => b -> a -> a or op :: forall a b. (C a, Ord b) => b -> a -> a }}} Answer: wer get the former. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12553#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler