Re: [GHC] #11458: Terrible failure of type inference in visible type application

#11458: Terrible failure of type inference in visible type application -------------------------------------+------------------------------------- Reporter: simonpj | Owner: goldfire Type: bug | Status: new Priority: highest | Milestone: 8.0.1 Component: Compiler (Type | Version: 7.10.3 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 Richard Eisenberg ): In [changeset:"00cbbab3362578df44851442408a8b91a2a769fa/ghc" 00cbbab3/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="00cbbab3362578df44851442408a8b91a2a769fa" Refactor the typechecker to use ExpTypes. The idea here is described in [wiki:Typechecker]. Briefly, this refactor keeps solid track of "synthesis" mode vs "checking" in GHC's bidirectional type-checking algorithm. When in synthesis mode, the expected type is just an IORef to write to. In addition, this patch does a significant reworking of RebindableSyntax, allowing much more freedom in the types of the rebindable operators. For example, we can now have `negate :: Int -> Bool` and `(>>=) :: m a -> (forall x. a x -> m b) -> m b`. The magic is in tcSyntaxOp. This addresses tickets #11397, #11452, and #11458. Tests: typecheck/should_compile/{RebindHR,RebindNegate,T11397,T11458} th/T11452 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11458#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler