#13324: Allow PartialTypeSignatures in the instance context of a standalone deriving declaration -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #10607 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): bgamari, yes, I believe #8510 is what you are looking for. I don't think that implementing this feature would be that difficult, either, since: 1. We already have a `Extension` datatype for representing all GHC extensions 2. The GHC API already has `setXOptM`/`unsetXOptM` for enabling/disabling `Extensions` within the scope of some computation So I think we'd just need a Template Haskell function `qWithExtensions :: Quasi m => [OnOff Extension] -> m a -> m a` that enabled/disables whatever the user provides. Then libraries like `deriveTopDown` could just use `qWithExtensions [On PartialTypeSignatures]` to wrap any splices that contain wildcard types. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13324#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler