#11715: Constraint vs * -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler (Type | Version: 8.0.1-rc1 checker) | Resolution: | Keywords: Typeable 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 goldfire): Flipping back through this ticket, I see that my new comment:47 seems to appear out of the blue. I also see @int-index advocating for dropping the distinction between `Constraint` and `Type` entirely.... but a quick skim doesn't show others agreeing with this direction of travel. I ''do'' think @int-index's approach (allowing `Int => ...`) is plausible, but I still am not convinced it's a good idea. If it's the ''only'' way to solve the original ticket, then perhaps it would be worth revisiting, but I'm not keen to start down that road. @int-index, you have argued well for your cause, but I, personally, need to see others agree with you and want these features before getting on board. It's not a matter of soundness or implementation, but of the kind of features and properties we wish Haskell to have. Responding more directly to comment:50: 1. That's true I suppose. We could also say, though, that `RuntimeRep` tells us the calling convention, not just the runtime representation. Constraints and regular types ''do'' have different calling conventions in Haskell code. 2. This goes back to my paragraphs above, in this comment. 3. `reflection` is an abuse of GHC, using an undocumented feature of the implementation. I do understand that many people use this undocumented feature, and so we could look at a way of saving `reflection`, but I don't see this as an argument against my proposal. We could always come up with another way to support `reflection` without newtype-classes. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11715#comment:51 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler