About two weeks have passed since this was first proposed, and there doesn't seem to be any definite consensus. In fact, I'm not sure if you even want this to be implemented anymore, since you seem reticent to give up the ability to define custom `Generic` instances. If you do wish to
#13065: Prohibit user-defined Generic and Generic1 instances -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature request | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Generics Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by dfeuer): Replying to [comment:8 RyanGlScott]: pursue this further, I'd highly recommend creating a GHC proposal for it, since this seems to be a topic of contention. I am of two minds. I see very good reasons to make this change, and I see very good reasons to be wary of it. I'm not the main person pushing for it; I'm just the one who wrote it up. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13065#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler