#9568: Type classes that fully cover closed kinds -------------------------------------+------------------------------------- Reporter: dmcclean | Owner: Type: feature | Status: new request | Milestone: ⊥ Priority: lowest | Version: 7.8.3 Component: Compiler | Keywords: (Type checker) | Architecture: Unknown/Multiple Resolution: | Difficulty: Unknown Operating System: | Blocked By: Unknown/Multiple | Related Tickets: Type of failure: | None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by goldfire): I agree fully with Reid (rwbarton). Those "class constraints" are really, under the hood, implicit parameters (dictionaries) passed around at runtime. Given that they have runtime significance, I don't think it's a good idea to hide them from the programmer. On the relationship to Pi-types: As described in [https://www.youtube.com/watch?v=O805YjOsQjI this video] and [wiki:DependentHaskell this wiki page], I'm working on a version of GHC that allows a type parameter to be made available at runtime. This feature could be used to simulate dictionary passing (I believe), by examining the type parameter at runtime and making decisions based on it. So, I guess this might improve the syntax a bit -- hard to say for sure at this point. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9568#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler