#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 simonpj): Do you also, as #13415 implies, want the non-`deriving` case to work? {{{ instance _ => C (T a) where op x = ... bop y = ... }}} This would be more ambitious, because you'd have to infer the constraints for the arbitrary user-written code in "...", and `TcInstDcls` isn't set up to do that. Remember that two instance declarations might both need each other. That's why there's a fixpoint in the deriving code. I think it'd be a lot easier to handle the deriving case than the general case. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13324#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler