#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): This behavior is all expected... or, in one case, not unexpected. The very first example in the OP is regrettable, but it is "not unexpected", as `-XNoTypeInType` rejects such programs on a best-effort basis. That one is hard. The other examples are all consequences of [https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts... #complete-user-supplied-kind-signatures-and-polymorphic-recursion the CUSK rules]. Proposed solution: allow top-level kind signatures of type-level declarations (just like we have top-level type signatures of term-level declarations) and deprecate CUSKs. One Of These Days, I will write a ghc- proposal for this. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13761#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler