[swift-evolution] [swift-evolution-announce] [Review] SE-0120: Revise 'partition' Method Signature

Paul Cantrell cantrell at pobox.com
Tue Jul 12 14:25:47 CDT 2016

The proposal is clearly an improvement over the status quo.

A naming concern, which I apologize for not getting in before the review period:

In Ruby (and I think some other languages as well), “partition” returns two collections, one with the included elements and one with the excluded. That’s a useful flavor of the method to have. I’ve added it in an extension myself in a project or two.

Does this proposal leave room for the two-collection variant if we want to add it later?

If it were to honor the existing term of art, the natural name for it would be “partitioned(by:)”:

    mutating func partitioned(by: …) -> ([Self.Iterator.Element], [Self.Iterator.Element])

However, naming the in-place reordering method “partition” as this proposal does would suggest instead that “partitioned(by:)” is instead its non-mutating counterpart:

    mutating func partitioned(by: …) -> ([Self.Iterator.Element], Index)

Overloading on return type is dicey business, especially when the type resolver has to peer inside a tuple. Could these two flavors coexist peacefully? Will this be confusing? Are we painting ourselves into a corner?



> On Jul 12, 2016, at 1:12 PM, Chris Lattner <clattner at apple.com> wrote:
> Hello Swift community,
> The review of "SE-0120: Revise ‘partition' Method Signature" begins now and runs through July 19. The proposal is available here:
> 	https://github.com/apple/swift-evolution/blob/master/proposals/0120-revise-partition-method.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?
> 	* 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?
> 	* If you have used other languages or libraries with a similar feature, how do you feel that this proposal compares to those?
> 	* How much effort did you put into your review? A glance, a quick reading, or an in-depth study?
> 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
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