#13674: GHC doesn't discharge heterogeneous equality constraint when it ought to -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by oerjan): I assume the difference, as usual in these kinds of tricks, is that in the workaround, GHC never gets directly asked to produce `Lcm m m ~ m` as a wanted constraint, and so never gets a chance to smell anything fishy. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13674#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler