I played around with your example a bit and came up with the following construction, which isn't the most beautiful but works in GHC 8.0 (so in
There are two things going on here
* Allowing uppper-case names for overloaded labels. This sounds
#11671: Allow labels starting with uppercase with OverloadedLabels -------------------------------------+------------------------------------- Reporter: inaki | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc1 (Parser) | Resolution: | Keywords: ORF 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 inaki): Replying to [comment:9 adamgundry]: particular, I've lowercased the label names): Clever :) Replying to [comment:10 simonpj]: plausible to me, although I have not thought through the consequences.
* Some form of overloading for pattern matching, building on pattern
synonyms. Certainly sounds interesting, but should really have its own ticket and wiki page. Indeed! I thought it may be an straightforward feature request, but now I am not sure. Honestly, the realization that they cannot be (straightforwardly) pattern matched against removes quite a bit of my original motivation (detailed in comment:2) for asking this. So the fact that they are not really patterns may make it a good thing that they cannot start by uppercase, so one is not tempted to match against them. In any case I can certainly file a new ticket with the feature request for "OverloadedPatterns", if you think that's useful. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11671#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler