#12014: Make it possible to deprecate a method instantiation of a typeclass instance -------------------------------------+------------------------------------- Reporter: niteria | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | Keywords: 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 simonpj): Good idea in principle -- but fragile. E.g. {{{ f :: Eq a => a -> a -> Bool f x y = not (x == y) blah = f Foo Foo }}} At the call of `f` GHC can't see that you are ultimately going to use the `(==)` method of the `Eq` dictionary passed to `f`. So would you expect to get a deprecation message here? If you think about what it translates to, it's a bit like {{{ blah = f (eqFoo, neqFoo) Foo Foo }}} where the tuple argument is the dictionary. If you wrote it like that you'd get deprecations for both `eqFoo` and `newFoo` even though only one of them is ultimately actually called. I don't think I see a useful, robust path here, yet. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12014#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler