#10928: Refine pattern synonym signatures -------------------------------------+------------------------------------- Reporter: mpickering | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.10.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): -------------------------------------+------------------------------------- Comment (by goldfire): I like the idea of using a different operator to flag required vs provided here. I'm far from convinced about `*>`, not in the least because that steals the type operator. I do agree with Reid about the unfortunate fact that `C a => D a => T` already has a meaning. But we're not stealing syntax here, because the `blah` in `pattern P :: blah` is '''not''' a type. It's a pattern type signature, which, in its current syntax, looks rather like a type, but it's a different beast, with its own strange rules. (Rather like the fact that the `blah` in `data X where Y :: blah` is also not a type. Note that `C a => D a => a -> X` doesn't work there, but that record and bang syntax does.) So I'm not terribly bothered by the double `=>` in this regard, but only a little bothered. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10928#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler