#13116: Allow Overloaded things in patterns -------------------------------------+------------------------------------- Reporter: | Owner: facundo.dominguez | Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by facundo.dominguez: @@ -18,2 +18,2 @@ - Do ((==) (fromLabel (proxy# :: Proxy# "foo")) -> True) -> ... - Don't ((==) (fromLabel (proxy# :: Proxy# "foo")) -> True) -> ... + Do ((==) (fromLabel (proxy# :: Proxy# "block")) -> True) -> ... + Don't ((==) (fromLabel (proxy# :: Proxy# "block")) -> True) -> ... New description: This ticket is motivated by the use of `OverloadedLabels` of the [http://hackage.haskell.org/package/choice-0.2.0 choice package]. One can use a type `Choice "block"` with values `Do #block` and `Don't #block` by using `OverloadedLabels`. However, in patterns this syntax is forbidden. {{{ case block of Do #block -> ... Don't #block -> ... }}} It would be nice if overloaded labels desugared to something sensible in patterns, perhaps {{{ case block of Do ((==) (fromLabel (proxy# :: Proxy# "block")) -> True) -> ... Don't ((==) (fromLabel (proxy# :: Proxy# "block")) -> True) -> ... }}} `OverloadedLists` and `OverloadedStrings` could benefit from a similar solution. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13116#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler