[swift-evolution] [swift-evolution-announce] [Review] SE-0111: Remove type system significance of function argument labels

[Charlie Monroe]

> On Jul 4, 2016, at 1:36 PM, Vladimir.S via swift-evolution <swift-evolution at swift.org> wrote:
> 
> On 04.07.2016 14:17, Brent Royal-Gordon via swift-evolution wrote:
>>> 	* What is your evaluation of the proposal?
>> 
>> I agree that the current situation is incoherent. If the type system doesn't care about the labels, the labels probably shouldn't be in the type.
>> 
>> In the long run, it must be possible to label the parameters of a closure. But that labeling does not *necessarily* belong on the type; it could go on the name:
>> 
>> 	// Old and busted
>> 	let completion: (records: [Record]?, error: Error?) -> Void
>> 	// New hotness
>> 	let completion(records:error:): ([Record]?, Error?) -> Void
>> 
> 
> I really like this idea. Clearly separated "name" and "type" of the function/closure just like for like for any other "simple" variable like `let value: Int`
> The only note : I believe we should be still allowed to define func variable without labels, if I don't care about them.
> 
> let completion: ([Record]?, Error?) -> Void
> 
>> And I don't think it would be terrible to remove the labels from the type before we add them to the name.
>> 
> 
> Support. But it will be great if we'll have both at the same time.

The question is how is this affecting current code base? Remove the labels for Swift 3 and then adding them back in subsequent Swift release - but the labels are already removed from the code... Is this really something we need to have *right now*, instead of waiting for a bit and adding an automatic migration?

I know it's a code-breaking change, but I don't think Swift 3.x or Swift 4 will be completely 100% code-compatible, even though it's one of the goals of Swift 3 to make as many code-breaking changes as possible...

> 
>> On the other hand, we could go the other direction and make the labels significant. Or—to address the `remove(from:)`/`add(to:)` critique—we could perhaps make the *internal* names significant, while considering the internal labels as part of the variable name. (Presumably both `remove(from:)` and `add(to:)` would be of type `(collection: WidgetCollection) -> Void`.)
> 
> I don't feel like this is correct direction. For me parameter labels definitely belongs to name of func variable, not to type.
> 
>> 
>> Both options are sensible; the status quo is not. We should choose a direction and start going that way.
>> 
>>> 	* Is the problem being addressed significant enough to warrant a change to Swift?
>> 
>> Yes. The type system is being a bit nonsensical here.
>> 
>>> 	* Does this proposal fit well with the feel and direction of Swift?
>> 
>> Yes. Swift 3, breaking everything now, etc.
>> 
>>> 	* If you have used other languages or libraries with a similar feature, how do you feel that this proposal compares to those?
>> 
>> Can't really think of much that's comparable.
>> 
>>> 	* How much effort did you put into your review? A glance, a quick reading, or an in-depth study?
>> 
>> Quick reading.
>> 
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