#12569: TypeApplications allows instantiation of implicitly-quantified kind variables -------------------------------------+------------------------------------- Reporter: vagarenko | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Keywords: Resolution: | TypeApplications 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 adamgundry): Ah, I imagined that the left-to-right collection and topological sorting of variables applied only when there wasn't an explicit `forall`. My expectation was that if the user gives an explicit `forall`, only the binding occurrences would be available for visible type application. Thus `forall (x :: k)` would make `x` available alone, whereas `forall k (x :: k)` would make both `k` and `x` available. I think this alternative would be better, because otherwise there is no way to get at `forall {k} (x :: k)`, is there? Unless we permit visibility annotations in concrete syntax, I suppose... In any case, this deserves explicit mention in the manual, including the `forall (x :: k)` example, whichever treatment it ends up getting. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12569#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler