#12432: Use kind equality in instance context in type family instance -------------------------------------+------------------------------------- Reporter: j6carey | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: Operating System: Linux | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by goldfire: @@ -7,0 +7,4 @@ + + EDIT: This ticket got repurposed at comment:3 and below. The original + problem described above is fixed, but the commentary is useful to keep + around and on this ticket. New description: With TypeInType enabled, I can use a closed type family to compute the return kind of a type family from its arguments. But an equivalent open type family used in the same way triggers a compilation failure, as if the relevant instance of that open type family were not considered. (Of course, there may be some subtle prohibition of which I am not aware at the present time.) I will attach a test case. EDIT: This ticket got repurposed at comment:3 and below. The original problem described above is fixed, but the commentary is useful to keep around and on this ticket. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12432#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler