#9107: An alternative to witness values ----------------------------+---------------------------------------------- Reporter: | Owner: spacekitteh | Status: new Type: feature | Milestone: request | Version: 7.9 Priority: normal | Keywords: Component: | Architecture: Unknown/Multiple Compiler | Difficulty: Moderate (less than a day) Resolution: | Blocked By: Operating System: | Related Tickets: Unknown/Multiple | Type of failure: | None/Unknown | Test Case: | Blocking: | ----------------------------+---------------------------------------------- Comment (by spacekitteh): Such an extension would appear to be relatively straightforward to implement, by simply adding extra constraints to the typechecker at the call site, and removing the "The class method 'measure' mentions none of the type variables of the class Metric k a" error during compilation of the typeclass. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9107#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler