#9223: Type equality makes type variable untouchable -------------------------------------+------------------------------------- Reporter: Feuerbach | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 (Type checker) | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by goldfire): Interesting example! I'm not convinced this is related to the original ticket, but it is curious. I do see why !OutsideIn refuses to type-check this, in the presence of the GADT pattern-match on `TokIntLit`. But what's interesting to me is that I can't come up with a type other than `Token TokenType -> Integer` for `foo`. As I note above, usually when we get untouchable variable errors, there is an alternate type that could be assigned... but here, that doesn't seem to be the case, because the GADT pattern-match is happening over an existentially-bound variable. I don't know what the fix is here, but it's an interesting case. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9223#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler