[swift-evolution] [Pitch] Replace the ternary operator with an in-language function

[Jay Abbott]

David,

You make some good points in favour of explicit support for user-defined
ternary operators. You're right that it's a bit clunky without. Probably a
discussion for another thread though, and additive so not for phase 1. But
perhaps worth a proposal for phase 2?

On Thu, 27 Oct 2016 at 09:23 David Sweeris <davesweeris at mac.com> wrote:

>
> On Oct 26, 2016, at 21:29, Jay Abbott <jay at abbott.me.uk> wrote:
>
> David, you can use two binary operators (or overload the same one twice if
> you want) to create syntax that behaves like a ternary operator.
>
> Oh I know, it's just kinda clunky and inefficient sometimes, if you need
> to wrap a value in a struct or something simply to avoid ambiguity or
> enforce the correct syntax. It's not quite the same thing a ternary
> operator, but at one point I'd added `|` as both pre and postfix operators
> to allow code like "let y = |x|". The left `|` had to return a
> `_PartialAbsValueOp` and the right one had to take the same to invalidate
> the "let y = |x" or "let y = x|" syntax, one of which would've otherwise
> worked (depending on which op actually called "abs()").
>
> I should've been clearer that I was talking about support for "free form"
> operators in general, including ternary ops, so that we don't have to fake
> them by declaring some # of traditional pre/in/postfix operators which all
> then have to work together (possibly exclusively, depending on the desired
> syntax), and might have to pass wrapper types around solely to help explain
> your syntax to the compiler.
>
> Thanks for pointing it out, though. That's an easy trick to forget about.
>
> - Dave Sweeris
>
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