#15151: Better Interaction Between Specialization and GND -------------------------------------+------------------------------------- Reporter: andrewthad | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Research | needed Component: Compiler | Version: 8.4.2 Resolution: | Keywords: 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 andrewthad):
In short, it feels like there ought to be a more general guiding principle here to determine whether two instance dictionaries are representationally equivalent. I'm not sure what that would be, though.
That seems to sum up the difficulty pretty well. I agree that giving GNDed instances special standing would be bad (and difficult, since that's currently not even tracked). I have no idea what a good way to check instance equality would be. I don't expect that this will be doable in the immediate or even in the far future, but maybe it's a research problem someone may try to tackle one day. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15151#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler