#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: | Operating System: Unknown/Multiple Differential Revisions: Phab:D69 | Type of failure: None/Unknown Architecture: | Test Case: Unknown/Multiple | Blocking: Difficulty: Unknown | Blocked By: | Related Tickets: #1241, | #2247, #8356, #9103, #9227 | -------------------------------------+------------------------------------- Comment (by sulzmann): You should be fine in the situation you describe above. The type inferencer is faced with a single constraint CText X t for some t which is then reduced to t = m Int, Monad m In my example I assume two occurrences of method f which result in F [a] [b], F[a] c This leads then to a conflict between the FD and the instance rule. Hence, we find two distinct final constraint stores (1) and (2). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8634#comment:28 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler