swiftlang/swift

[SR-6864] Add a "cycle" method to the standard library

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#49,413 opened on Jan 29, 2018

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featuregood first issuestandard libraryswift evolution proposal needed

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Description
Previous ID SR-6864
Radar None
Original Reporter @airspeedswift
Type New Feature
Votes 0
Component/s Standard Library
Labels New Feature, StarterProposal
Assignee None
Priority Medium

md5: ce3f8a07c6a7edad8e1997fb1e825980

Issue Description:

It is often useful to cycle over a sequence indefinitely. For example, just like you can write zip(repeatElement("foo", count: Int.max), myArray) and zip(1..., myArray), you could write {{zip([.grey,.white].cycle(), myArray)}}.

Contributor guide

Research direction
Study the Sequence protocol in the Swift standard library to understand the pattern for adding methods that return sequences. Look at existing methods like repeatElement and stride for reference. Implement a cycle method that returns an infinite sequence cycling through the elements. Write unit tests to verify behavior.
Tech stack
swift
Domain
api
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Swift
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80