#7766: equality constraints exposed by patterns mess up constraint inference --------------------------------------+------------------------------------- Reporter: heisenbug | Owner: Type: bug | Status: new Priority: normal | Component: Compiler Version: 7.7 | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: GHC rejects valid program | Blockedby: Blocking: | Related: --------------------------------------+------------------------------------- When patterns bring (equality) constraints into scope, the inference mechanism for other (unrelated) constraints breaks down. This is a new problem that appeared between * ghc-7.7.20121025 and * ghc-7.7.20121114 I can try to track down the commit if that helps. Testcase against HEAD attached. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7766 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler