#5144: Pattern synonyms -------------------------------------+------------------------------------ Reporter: simonpj | Owner: cactus Type: feature request | Status: new Priority: normal | Milestone: _|_ Component: Compiler | Version: Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by cactus): I've implemented infix notation as well, so now you can write this: {{{ {-# LANGUAGE ViewPatterns, PatternSynonyms #-} import qualified Data.Sequence as Seq pattern Empty = (Seq.viewl -> Seq.EmptyL) pattern x :< xs = (Seq.viewl -> x Seq.:< xs) pattern xs :> x = (Seq.viewr -> xs Seq.:> x) zipZag :: Seq.Seq a -> Seq.Seq b -> Seq.Seq (a, b) zipZag (x :< xs) (ys :> y) = (x, y) Seq.<| zipZag xs ys zipZag _ _ = Seq.empty }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/5144#comment:18 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler