[swift-evolution] History and future of Swift's parentheses

Jens Persson jens at bitcycle.com
Mon Jun 12 13:36:30 CDT 2017

On Mon, Jun 12, 2017 at 7:13 PM, Michael Ilseman <milseman at apple.com> wrote:
> * Unless you’re proposing a change to the semantics of the language that
> could affect e.g. name mangling or the type metadata hierarchy, then that
> would be ABI-affecting. For example, proposing that all functions must only
> take a single tuple rather than multiple arguments could affect the runtime
> representation of function types. But even then, there are approaches to
> mitigate this, so such a proposal would likely present an ABI migration
> strategy.
I think I understand (and understood), in very basic terms, the difference
between source stability and binary stability, and I was thinking something
like this:

What if there is a chance that the "uniform tuple concept" could be
redesigned and reimplemented after all, handling inout, variadic, etc in
some way, allowing named single element tuples, allowing A -> B to
represent (possibly only "pure") functions with _any_number_ of args, and
not just one, as in Swift 4, and so on.

I'm still not entirely sure if this is ABI-affecting or not. But anyway,
thank you for your calming words!

(I will try to not worry that (almost) everything parentheses-related in
Swift will forever be stuck in a local optimum, because its current state
and the history that lead to it is so confusing that it will stop all
attempts at a substantially better solution and only allow minor

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