# \[Accepted\] SE-0270: Add \`Collection\` operations on noncontiguous elements **URL:** \ **Category:** Announcements\ **Tags:** collection, stdlib\ **Created:** [December 20, 2023, 12:41am UTC](https://forums.swift.org/t/accepted-se-0270-add-collection-operations-on-noncontiguous-elements/69080 "2023-12-20T00:41:04Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![John\_McCall](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/john_mccall/32/1351_2.png) [@John\_McCall](https://forums.swift.org/u/John_McCall)\ **Post date:** [December 20, 2023, 12:41am UTC](https://forums.swift.org/t/accepted-se-0270-add-collection-operations-on-noncontiguous-elements/69080/1 "2023-12-20T00:41:04Z")
Hello, everyone. The [fourth review](https://forums.swift.org/t/se-0270-fourth-review-add-collection-operations-on-noncontiguous-elements/68855) of [SE-0270: Add `Collection` operations on noncontiguous elements](https://github.com/apple/swift-evolution/blob/main/proposals/0270-rangeset-and-collection-operations.md) ran from December 6th through the 18th. This review was both a re-review of the old proposal as part of accepting it into the standard library and a _de novo_ review of several small revisions to the proposal, which were described in the review announcement. Feedback during the review centered on two issues, which the Language Steering Group discussed while considering the proposal. The first issue is whether `RangeSet` is an appropriate addition to the standard library. `RangeSet` is unquestionably a specialized data structure with much narrower applicability than, say, `Dictionary`. The LSG has generally resisted adding data structures like this to the standard library, and we would likely not make an exception for `RangeSet` as a standalone addition. However, `RangeSet` is not a standalone addition; it is part of a proposal to add a number of algorithms on noncontiguous collection elements. These algorithms are best expressed in the standard library, and they need to be expressed using a type like `RangeSet` in order to avoid various inefficiencies. In that context, the LSG feels it makes more sense to accept a specialized collection like `RangeSet` to the standard library than to accept a less efficient API. The second issue is the naming of various APIs, particularly `RangeSet` and the `indices` methods that produce `RangeSet`s of indices from collections. Some reviewers felt this was inconsistent and argued for different names for one or the other. The LSG is satisfied with the names in the proposal. `RangeSet` is a general data structure; as discussed above, it has relatively narrow applicability, but it is broader than just sets of collection indices, and the LSG feels that it ought to have a name befitting that generality. Similarly, the LSG thinks it's fine for method names like `indices(of:)` to not convey that they return a `RangeSet` specifically; a `RangeSet` conceptually represents a set of indices, which matches the method name perfectly well. Accordingly, SE-0270 has been **accepted**. I'd like to thank everyone who participated in this review, both this iteration and all the prior rounds. Your contributions help to make Swift a better language. John McCall Review Manager