#11008: Difficulties around inferring exotic contexts -------------------------------------+------------------------------------- Reporter: crockeea | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 Resolution: | 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 crockeea): Without knowing anything about the internals of GHC, it seems there are two ways to simplify instance contexts: either we "simplify and reject" if they are "exotic" (in the case of GND instances), or just "simplify and typecheck" (in the case of hand-written instances of any variety). So if an instance head matches (Eq (Foo r)), trigger the "simplify and typecheck" rather than "simplify and reject exotic constraints" behavior. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11008#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler