#8171: Extending ExtendedDefaultRules -------------------------------------+------------------------------------ Reporter: ekmett | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by ekmett): Personally, I think that sounds like a pretty good fix. I'd want to float it past the libraries mailing list to see what issues folks can foresee, but literally none of the packages I maintain on hackage would have an issue with this change, but you already get a warning with -Wall for defaulting, and all programs that typechecked before would necessarily continue to typecheck, more defaulting would work by default in future code though. This interacts with the current libraries discussion on how to improve the rules about the shape of constraints (C1 a1, ...) to make it possible to support defaulting IsString when something like `length "hello"` on an OverloadedString happens. With appropriate rephrasing of the conditions on the constraints above, we may be able to consolidate support both of these scenarios. That said, I'm not sure off the top of my head how to rephrase that condition on the initial batch of constraints. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8171#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler