#9103: hackage's type-level-0.2.4 fails to compile ----------------------------------------------+---------------------------- Reporter: slyfox | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler (Type checker) | Version: 7.8.2 Resolution: invalid | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects valid program | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: #8634 ----------------------------------------------+---------------------------- Changes (by rwbarton): * status: new => closed * resolution: => invalid * related: => #8634 Comment: The error looks correct to me. {{{ class Succ' xh xl yh yl yz | xh xl -> yh yl yz, yh yl yz -> xh xl instance Failure (PredecessorOfZeroError x) => Succ' (x,x) (x,x) D0 D0 True }}} The functional dependency `yh yl yz -> xh xl` is violated because `D0 D0 True` do not determine `(x,x) (x,x)`: `x` is free. An instance of #8634. I'm going to mark this ticket as invalid (since it seems to me that you are considering this as a regression rather than a feature request), but see that ticket and its related tickets for ongoing discussion. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9103#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler