Swift Standard Library Preview Maintained?


This is my first post on the forums and I apologize if I’m not following any standard post guidelines, but I was finally getting around to some WWDC 20 videos when I watched What’s new in Swift. One of the things that piqued my interest was the Swift Standard Library Preview Open Source project especially with conversations surrounding async await and Actors.

It appears that this repo only really had the initial release over a year ago, but I guess I was hoping it would have had multiple releases since then for the various Minor Swift releases over the past year.

The repo states that it is supportive of contributions, but it doesn’t appear very descriptive in how I could support it. It appears as though it’s meant to be a collection of multiple SE-xxxx changes that are themselves separate repos under the Apple organization (at least that’s how it works for the single example that’s there currently).

Is this repo still maintained? If not, is the expectation to download the version of the Swift tool chain that has the upcoming changes in it to test instead?


Most proposals since then have been for the language or package manager. Of the few remaining proposals:

Swift Algorithms is also previewing ideas, specifically for sequence and collection algorithms.


@benrimmington thanks for the response and it sounds a bit more complex than I understood it to be. From what you’re saying though, it sounds like depending on the work done, the implemented proposals could go into one of many different locations for previewing purposes before it’s integrated in a release.

If you don’t mind me asking then, what are the qualifiers or types of proposals that would be showcased via the Swift Standard Library Preview package?

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Hi @JWShroyer — welcome to the Swift Forums!

The preview package is intended to support the Swift Evolution process by making certain kinds of additions easier to use in the period between acceptance and shipping in a new language release. In addition, a package-based approach can make it simpler for reviewers to try out proposed additions during the pitch and review phases. As @benrimmington noted, however, not all proposed features work well as a standalone package.

The preview package can include functionality that doesn’t depend on new language features or standard library internals. The criteria is explained most fully in the accepted proposal that created the package: swift-evolution/0264-stdlib-preview-package.md at main · apple/swift-evolution · GitHub.

New additions are landed in the preview package only after successful acceptance through Swift Evolution; the other packages that Ben mentioned are open to more direct collaboration through the issue and PR process on GitHub. I hope that helps!


@nnnnnnnn thank you for additional clarification! I knew I must’ve missed something. I’ll be more diligent to check for associated proposals on Swift evolution for more context in the future.

Thanks again! :grin:

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