#9757: Warn about derivable instances -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.9 Component: Compiler | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by goldfire): To my knowledge, GHC can ''not'' derive instances better than anyone else. Since the advent of `coerce`, `GeneralizedNewtypeDeriving` has no magic -- any GND instance can be written by hand, sometimes with lots of type annotations and `ScopedTypeVariables`, though. Personally, I would want to see nice definitions of "obviously" and "equivalent" before thinking too much harder about this. This seems hard to do and not terribly useful, to me. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9757#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler