#8634: Relax functional dependency coherence check ("liberal coverage condition") -------------------------------------+------------------------------------- Reporter: danilo2 | Owner: Type: feature | Status: new request | Milestone: 7.10.1 Priority: high | Version: 7.7 Component: Compiler | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: #1241, #2247, None/Unknown | #8356, #9103, #9227 Test Case: | Blocking: | Differential Revisions: Phab:D69 | -------------------------------------+------------------------------------- Comment (by goldfire): About unpredictability: I think this is quite similar to `IncoherentInstances`, where, I believe, similar unpredictability exists. A notable difference here is that `DysfunctionalDependencies` would introduce compile-time unpredictability. I would say, though, that it is up to the user to make sure that their dysfunctional dependencies are confluent w.r.t. the equivalence relation that is relevant to them -- which might not be `(~)`. So, I think there's support for this feature. What needs to be done to merge? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8634#comment:52 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler