At least it incites a reaction :) the proposal was but we can go into
#13403: Derive instances (Applicative, Monad, ...) for structures lifted over functors -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: 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 RyanGlScott): Replying to [comment:3 Iceland_jack]: the direction of [https://hackage.haskell.org/package/base-4.9.1.0/docs /GHC-Generics.html#t:Rep Generic's Rep] Funny enough, I was going recommend exactly `GHC.Generics` as a solution to your problem. It gives you the power to exclude awkward subsets of datatypes (e.g., no `Monad` instances for `Compose`-like things), and it requires no changes to GHC. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13403#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler