> On Oct 25, 2016, at 10:30 PM, Charlotte Angela Tortorella via swift-evolution
> <[email protected]> wrote:
>
>> Not a replacement for the Swift 4 source stability goal.
>
> Swift 4 doesn't actually have a source stability goal. It has an ABI
> stability goal. These are two very different things. ABI is the calling
> conventions of the language.
Hi Charlotte,
Swift 4 has a strong source level compatibility goal. This is explained in the
main swift-evolution page and also in the proposal template:
https://github.com/apple/swift-evolution/blob/master/0000-template.md
<https://github.com/apple/swift-evolution/blob/master/0000-template.md>
"Relative to the Swift 3 evolution process, the source compatibility
requirements for Swift 4 are much more stringent: we should only break source
compatibility if the Swift 3 constructs were actively harmful in some way, the
volume of affected Swift 3 code is relatively small, and we can provide source
compatibility (in Swift 3 compatibility mode) and migration.”
I agree with you that a migrator could handle this change, but such a
significant source breaking change still needs major justification for doing
so. Further in the Swift 3 timeframe, this very topic was hotly debated by the
folks who wanted to turn the if statement into an expression (eliminating the
need for the ?: operator).
-Chris
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