#9242: Implement {-# OVERLAPPABLE #-} and {-# INCOHERENT #-} pragmas -------------------------------------+------------------------------------- Reporter: simonpj | Owner: diatchki Type: feature | Status: closed request | Milestone: Priority: normal | Version: 7.8.2 Component: Compiler | Keywords: Resolution: fixed | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by simonpj): * status: new => closed * resolution: => fixed Comment: I have finally done the INCOHERENT thing. I'll close this ticket. There are some loose ends which I'll list here: * David, if you want to open a new ticket for OVERLAPS, by all means do so, if you think you've got a good proposal with user support. * I'd like to make `-XUndecideableInstances` a per-instance pragma, instead of a module-wide LANGUAGE flag. That would be consistent with this `OVERLAPPABLE` stuff. Anyone want to do that? * At least one person suggested that there should be a LANGUAGE pragma that switches on recognition of the per-instance pragmas. So `{-# OVERLAPPABLE #-}` is only honoured if you have `-XHonourOverlappingInstnaces` or something. Personally I think this is too much, but users may differ! Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9242#comment:36 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler