#9757: Warn about derivable instances -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- GHC can derive a lot of instances by itself, and can sometimes (with `GeneralizedNewtypeDeriving`) do so better than anyone else. I'd like to be able to get a warning about any instance that's "obviously equivalent" to the one that would be derived, for some suitable values of "obviously" and "equivalent". -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9757 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler