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

Tony Allevato allevato at google.com
Fri Jul 1 18:36:45 CDT 2016

On Thu, Jun 30, 2016 at 11:26 AM Chris Lattner via swift-evolution <
swift-evolution at swift.org> wrote:

> Hello Swift community,
> The review of "SE-0111: Remove type system significance of function
> argument labels" begins now and runs through July 4. The proposal is
> available here:
> https://github.com/apple/swift-evolution/blob/master/proposals/0111-remove-arg-label-type-significance.md
> Reviews are an important part of the Swift evolution process. All reviews
> should be sent to the swift-evolution mailing list at
>         https://lists.swift.org/mailman/listinfo/swift-evolution
> or, if you would like to keep your feedback private, directly to the
> review manager.
> What goes into a review?
> The goal of the review process is to improve the proposal under review
> through constructive criticism and contribute to the direction of Swift.
> When writing your review, here are some questions you might want to answer
> in your review:
>         * What is your evaluation of the proposal?

+1. I'm in agreement with others in this thread who say that the labels are
parts of the *name* of the function, not parts of its *type*. If I
understand the other discussions regarding the evolution of Swift's
function arguments model, the similarity to tuples with labeled components
is a historical artifact and now merely coincidental.

The analogy to Objective-C here is obvious, where you have selectors
instead of functions. The selector is the "name" of the "function" and it
contains all of the parts, not just the base name.

Swift function names to me are like German separable verbs. Even when
they're split across the sentence with multiple words in-between, the
prefix is still considered part of that verb, not a separate word/concept.

>         * Is the problem being addressed significant enough to warrant a
> change to Swift?


>         * Does this proposal fit well with the feel and direction of Swift?

Yes. This feels like a natural follow-up to SE-0021, which allowed the use
of argument names to differentiate between overloads with the same argument
types at the same positions. To me, this is another admission that the
labels are part of the function's *name*.

>         * If you have used other languages or libraries with a similar
> feature, how do you feel that this proposal compares to those?

Aside from Objective-C mentioned above, the other languages I've used that
have named/keyword arguments (like Python) are dynamic languages that treat
the incoming argument list as a dictionary; in that case, the language
design is significantly different and I can't draw an analogy between them.

>         * How much effort did you put into your review? A glance, a quick
> reading, or an in-depth study?

Read the proposal and loosely followed the discussion.

> More information about the Swift evolution process is available at
>         https://github.com/apple/swift-evolution/blob/master/process.md
> Thank you,
> -Chris Lattner
> Review Manager
> _______________________________________________
> swift-evolution mailing list
> swift-evolution at swift.org
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