#9023: Error when using empty record update on binary pattern synonym --------------------------------+--------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Linux Architecture: x86 | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | --------------------------------+--------------------------------- Using an empty record update with patterns works here {{{ pattern Singleton a = [a] isSingleton :: [a] -> Bool isSingleton Singleton{} = True isSingleton _ = False }}} but fails in the follow example (there may exist a more minimal example) {{{ pattern P a b = Just (a, b) foo P{} = True }}} which outputs (GHC 7.8.2) {{{ $ ghci -ignore-dot-ghci tmp.g2WZtTUkhJ.hs GHCi, version 7.8.2: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. [1 of 1] Compiling Main ( tmp.g2WZtTUkhJ.hs, interpreted ) Var/Type length mismatch: [t{tv aIW} [sk]] [] Ok, modules loaded: Main. *Main> }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9023 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler