So we really know their kinds from the type family declaration. There is no need to be able to write their kinds in the default equation. So
#16110: Explicit foralls in associated type family defaults are completely ignored? -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.7 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC accepts | Unknown/Multiple invalid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): perhaps the best way forward is just to remove the featurette. I agree. And let's update the proposal to match. We should also document whatever we decide (including the alpha-varying bit) in the user manual -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16110#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler