#13761: Can't create poly-kinded GADT with TypeInType enabled, but can without -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): I mean something like {{{#!hs type T :: k -> Type -- this is the kind signature data T _ where MkT :: T Int }}} Note that there is no `=` in the kind signature, distinguishing it from a type synonym declaration. The `_` in the `data` line is a recognition that a datatype with a kind signature does not need anything after the `T`. Not sure what the best concrete syntax around that is. (In my thought about this feature, `data T a where` and `data T :: ... where` would also both be acceptable.) Types with kind signatures will be treated just like types with CUSKs are today. Eventually, I would expect types without kind signatures to be treated just like types without CUSKs today. We would then cease to have a notion of CUSK. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13761#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler