> On Sep 18, 2016, at 6:24 PM, Xiaodi Wu via swift-evolution
> <firstname.lastname@example.org> wrote:
> On Sun, Sep 18, 2016 at 9:19 PM, Erica Sadun via swift-evolution
> <email@example.com <mailto:firstname.lastname@example.org>> wrote:
> Let me tl;dr'er this even more: ☹️ is an operator, but 🙂 is an identifier.
> -- E, succinct, who thinks there's room for improvement
> Ha, yes. Let's see if I can be as succinct in my contribution to the
> 1) Agree that current situation not ideal, for reasons above
+1, totally agreed. We really need to improve this, aiming for Swift 3.1 or
Swift 4 seems like a really good idea, because the appetite for this sort of
change will probably be very low after Swift 4.
> 2) The solution might best be not one but several proposals:
> 2a) Unicode normalization: invisible characters, Greek tonos, etc. (cf.
> previous message about previously proposed solution, which reflects Unicode
> recommendations in UTR #31)--low hanging fruit: there's an established
> Unicode recommendation with clear wins for security and consistency
> 2b) Legal and illegal characters for identifiers *or* operators: UTR #31
> makes recommendations regarding rarely used scripts; probably best to follow
> the letter and spirit of these recommendations (which would probably mean
> ancient Greek musical symbols and Egyptian hieroglyphics shouldn't be
> identifier or operator characters)
> 2c) Decisions as to which characters are identifier characters or operator
> characters: for instance, emoji should probably never be operator characters;
> if an emoji has a non-emoji counterpart that is an operator (❗️❓➕➖➗✖️, etc.)
> it might be best simply to make these illegal rather than operator characters
> 2d) Confusables: I think the last time we had this discussion, it was
> apparent that it'd be difficult to decide which confusables to allow or
> disallow after some of the low-hanging fruit is taken care of by Unicode
> normalization (see item 2a); the Unicode Consortium-provided list seems too
> quick to call two things "confusable" for our purposes (with criteria that
> might be relevant for URLs or other use cases, but casting too wide a net
> perhaps for Swift identifiers)
These all seem like good points. I agree that we should default to following
an existing Unicode standard unless there is a really good reason to deviate.
I don’t have an opinion about the specific direction of the proposal though.
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