#14661: Cannot derive (newtype I a b = I (F a -> F b) deriving newtype Category) for type family F -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: feature request | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 8.4.1-alpha1 Resolution: wontfix | Keywords: | DerivingStrategies, deriving, | TypeFamilies 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 Iceland_jack): Replying to [comment:9 simonpj]:
However, the new feature looks tantalisingly close.
This won't always work as Ryan points out, but sometimes. And I suppose we could work that out.
It seems rather elaborate though!
I agree that it's tantalising, if you think it's a general enough solution, enough “bang for the buck” then re-open. But there is no hurry on my end, I'd like more examples that need this. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14661#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler