#14065: Type inference -------------------------------------+------------------------------------- Reporter: zaoqi | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.2 checker) | Resolution: invalid | Keywords: 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 bgamari): To clarify, I've confirmed with Simon that this is indeed the expected behavior. The typechecker is conservative in inferring underneath pattern matches on equalities. See Chapter 6 of the [[http://research.microsoft.com/en-us/um/people/simonpj/papers/constraints /jfp-outsidein.pdf|OutsideIn paper]] to see the complications that arise when you try to infer under such matches. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14065#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler