#15639: Surprising failure combining QuantifiedConstraints with Coercible -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler (Type | Version: 8.5 checker) | Keywords: Resolution: | QuantifiedConstraints 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 dfeuer): malo, I don't think the problem you're encountering is related at all. You're hoping that `forall i. Coercible (f i) (g i)` will satisfy the `type role Bar representational nominal` requirement. But we don't have such an extensionality rule. Perhaps we could add one somehow, but that would be quite independent. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15639#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler