#11715: Constraint vs * -------------------------------------+------------------------------------- Reporter: bgamari | Owner: goldfire Type: bug | Status: new Priority: highest | Milestone: 8.4.1 Component: Compiler (Type | Version: 8.0.1-rc1 checker) | Keywords: Typeable, Resolution: | LevityPolymorphism, Roles 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 simonpj): Let me first note that we intend to make `Constraint` and `Type` distinct throughout the compiler. Then `tcView` = `coreView` again, and this entire problem goes away. We should not leave this too long. Until then we are looking for a ''sound'' solution, but it doesn't have to be a ''good'' solution. I'm puzzled about where the instance for `C Type Eq` comes from; after all, `Eq :: Type -> Constraint`. I wonder what would go wrong if we just used `coreView` for both class and family instances. I think (3); but I still don't see an example except perhaps with a polykinded type constructor e.g. `Typeable Type (Proxy Type)` and `Typeable Constraint (Proxy Constraint)`, and perhaps we can live with that for now. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11715#comment:70 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler