#9671: Allow expressions in patterns -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | Keywords: | PatternSynonyms Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Iceland_jack): Is this a matter of finding good syntax or is it something fundamental? I'll get the ball rolling, help me pick this apart {{{#!hs pattern Lookup \key val <- (lookup key -> Just val) pattern IsMember \val <- (member val -> True) -- and they get marked with $ when in pattern -- (I'm making this up on the tube) age (Lookup $"Alice" age) = ... -- Simon's f p (Lookup $p p) = p }}} If it helps we could impose a separation between "argument patterns" and patterns. I want this feature at least once a week ;) so I self-servingly remain +1 if this can be sorted -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9671#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler