#10607: Auto derive from top to bottom -------------------------------------+------------------------------------- Reporter: songzh | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 Resolution: | Keywords: deriving, | typeclass, auto 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 RyanGlScott): Hm... you know, that's a good observation. This approach does require another language extension (`PartialTypeSignatures`), but it certainly achieves the same end result. My only hesitation is that I don't understand `PartialTypeSignatures` that well, so I haven't fully considered the ramifications of allowing this. I'm fairly sure it would require a more complication implementation, since you'd also probably want to allow things like this: {{{#!hs deriving instance (C a, _) => C (T a b c) }}} But the prospect of not needing any changes to the language is a mighty tempting one. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10607#comment:16 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler