#13401: GHCi gives conflicting information about visible type application -------------------------------------+------------------------------------- Reporter: crockeea | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.0.1 Resolution: | Keywords: | TypeApplications Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #11376, #11975 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by crockeea): The reason I feel that GHCi is giving me incorrect info is due to the existing documentation that I quoted above. Basically, my understanding is that if `foo :: forall {k} . k` then GHCi should throw an error if I try to write `foo @Int`, and if `foo :: forall k . k`, then GHCi should happily accept `foo @Int`. When I see `foo :: forall {k} . k`, but GHCi also lets me write `foo @Int`, I have no idea what it means by `{k}`. This seems like a contradiction. I get the impression from your comments that there's something more subtle going on here that I don't understand. If you think others might have the same misconception as me, I would encourage you to improve the existing docs as well. In regards to your suggestion, I think it would be good to put a blurb in the Visible Type Application section (9.18 by my count) as well, near the "detail" note that explains the curly braces. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13401#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler