This is beyond my knowledge - I would require some guidance here. But if it's possible to implement injective type families without this change

#6018: Injective type families -------------------------------------+------------------------------------- Reporter: lunaris | Owner: jstolarek Type: feature | Status: new request | Milestone: 7.10.1 Priority: normal | Version: 7.4.1 Component: Compiler | Keywords: TypeFamilies, Resolution: | Injective Differential Revisions: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: #4259 | -------------------------------------+------------------------------------- Comment (by goldfire): Replying to [comment:41 jstolarek]: then I would postpone it until later and possibly consider it a separate task. Yes, it's possible, but there are some circumstances in which users could say that GHC gives an erroneous type error, in that GHC would manifestly have enough knowledge to make progress but doesn't. I agree that you should go ahead without this piece, though! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/6018#comment:42 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler