#11427: superclasses aren't considered because context is no smaller than the instance head -------------------------------------+------------------------------------- Reporter: phadej | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): It doesn't "reduce the normal language". It does reduce the scope of a tricky and ill-documented extension of Haskell, implemented by GHC, namely the ability to solve recursive instances. And it's tied up with an implementation trick called "silent superclasses" which I used to help, but which ultimately turned out to have several horrid and unforseen consequences. In short, I do not know now to do better. But maybe someone else will! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11427#comment:14 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler