#14070: Allow ‘unsafe’ deriving strategy, deriving code with ‘unsafeCoerce’ -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: | QuantifiedContexts, deriving 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:13 RyanGlScott]:
I'm pretty sure `QuantifiedContexts` should let us be able to use `GeneralizedNewtypeDeriving` in any situation where we need to `coerce` underneath a higher-kinded type parameter (like the `f` in `Lens (f a) a`).
Okay great
I mean, saying that you can derive everything that is derivable is a bit of a tautology.
It was a lazy question, I was wondering if there is anything GNDerivable in theory outside of GHC's reach even given quantified constraints (and your hunch).. Just as `join` is 'derivable' but is not derivable currently. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14070#comment:14 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler