[swift-evolution] [Review] SE-0032: Add find method to SequenceType

Max Moiseev moiseev at apple.com
Fri Apr 29 19:12:45 CDT 2016

HI all,

After having discussed this proposal with the members of the standard library team, we would like to propose the following updates:

- Since both the language and the standard library have evolved since it was written, the proposal should reflect these changes (things like renaming `Generator` to `Iterator`, adjusting for first argument label rules etc.)
(Actually, while writing this, I discovered https://github.com/apple/swift-evolution/pull/276)
- We believe that renaming `find(_:)` to `first(where:)` would make call sites more clear

// original proposal
numbers.find { isPrime($0) }

// suggested update
numbers.first { isPrime($0) }
numbers.first(where: isPrime)

In the examples above, when the predicate is passed as a trailing closure, there is no big difference in the invocation, but it changes when we have a named function that we would like to use as a predicate.
The Collection protocol already has a property called `first`, that returns an optional element, it also has a method `index(where:)`. In this sense `first(where:)` does not introduce new words to the library vocabulary.


> On Apr 28, 2016, at 11:11 AM, Chris Lattner via swift-evolution <swift-evolution at swift.org> wrote:
> Hello Swift community,
> The review of "SE-0032: Add find method to SequenceType" begins now and runs through May 3. The proposal is available here:
> 	https://github.com/apple/swift-evolution/blob/master/proposals/0032-sequencetype-find.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, eventually, determine 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 you 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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