Proposal: Allow Single Dollar Sign as Valid Identifier

[ankurp]

Swift should continue supporting use of $ as an identifier but when used with non-numeric name consider it an error.

→ View Proposal

[ankurp]

Any comments on this proposal?

[lattner]

This proposal looks in scope for Swift 3 for discussion, but I think it would be helpful if you improved the writing to make it more clear: I think what you're trying to say is that "$[0-9]+" is reserved for closure parameters, that $ by itself should be a valid identifier, and that "$[a-zA-Z_....]" (where the second character is something that would start a valid identifier) should be invalid.

[ankurp]

@lattner as you said. Rewording to make it clear.

[masters3d]

swiftlang/swift#3901

[masters3d]

@lattner with PR https://github.com/apple/swift/pull/3901/files already merged. This can be closed.

[ankurp]

I had suggested keeping the Dollar as valid identifier. If my PR is to be closed then it should have been done in June when I requested it and not wait until now by keeping it open. I created this PR in June then someone comes in August and merge their code that changes language syntax breaking a lot of existing code by doing opposite of what I suggested.

[lattner]

Hi @ankurp,

The core team discussed this today and would like to run this proposal for review by the swift-evolution community. Three requests:

1. please update it to the new proposal template: https://github.com/apple/swift-evolution/blob/master/0000-template.md
2. please do an editing pass to improve typos and the writing, for example there is a typo in the title.
3. Please mention that $ was never documented in the TSPL book.

Thanks!

[ankurp]

Thanks will update soon.

[lattner]

Thanks! Here is a link to TSPL:
https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/identifier

[ankurp]

Updated the proposal to be more clear. Looking forward to whatever the community decides.

[lattner]

Thanks! I'll merge this, make a few tweaks, and kick off review.