#9618: Undocument ImpredicativeTypes -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: | Version: 7.8.3 Documentation | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Easy (less than 1 Unknown/Multiple | hour) Type of failure: | Blocked By: Documentation bug | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by dfeuer): * failure: None/Unknown => Documentation bug * milestone: => 7.10.1 Old description:

I understand that Simon Peyton Jones intends to make `ImpredicativeTypes` work some day, but it doesn't work now. I think the thing to do for now is to remove it from the user manual. It can be put back in later if it's ever fixed.

New description: I understand that Simon Peyton Jones intends to make `ImpredicativeTypes` work some day, but it doesn't work now. I think the thing to do for now is to remove it from the user manual. It can be put back in later if and when it's fixed. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9618#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#9618: Undocument ImpredicativeTypes -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: | Version: 7.8.3 Documentation | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Easy (less than 1 Unknown/Multiple | hour) Type of failure: | Blocked By: Documentation bug | Related Tickets: #8808 Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by goldfire): I'm not convinced `ImpredicativeTypes` should be removed from the manual. Sometimes^[''citation needed'']^ I have needed `ImpredicativeTypes` to get my code to type check. `ImpredicativeTypes` isn't ''wrong'' -- it's just very, very rough around the edges. It won't (as far as I know) cause your code to segfault or otherwise go astray. The extension just doesn't work in all the contexts we might like it to. So, instead of removing it altogether, I think we should label it as experimental and very limited. That all said, I don't feel terribly strongly about this and am happy enough if the majority disagrees with me here. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9618#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler