
Now, the user chooses what facility provides the instances. Note that I've done something currently impossible: I've used GND for the `Read` class. Normally, we don't want this behavior, and (to my knowledge)
#10598: DeriveAnyClass and GND don't work well together -------------------------------------+------------------------------------- Reporter: osa1 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by oerjan): * cc: oerjan (added) Comment: Replying to [comment:3 goldfire]: there's no way to convince GHC to use GND to derive a `Read` or `Show` instance. But maybe some user out there does want it. I can think of at least one such use case that seems to make sense: Deriving `Read` and `Show` for newtypes around standard numeric types. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10598#comment:15 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler