Standard Library Preview Package

I’m excited to announce a new open-source package and an enhancement to the Swift Evolution process: the Standard Library Preview package! The preview package provides access to functionality that has been accepted into the Swift standard library through the Swift Evolution process, but has not yet shipped as part of an official Swift release. This will allow us to incorporate feedback informed by real-world usage and remove many of the technical obstacles to contributing to the standard library.

→ swift.org/blog/preview-package/

Swift 5 introduces the Standard Library Preview package, an open-source tool bundling accepted Swift Evolution features not yet in official releases, starting with SE-0270 for subrange operations like subranges(where:) and moveSubranges(_:to:) on collections, plus the RangeSet type.

This package lets developers test and provide feedback on new APIs via Swift Package Manager, re-exporting standalone modules for easy integration while maintaining a 0.x version for ongoing development. Proposals now include implementations as SPM packages submitted to a staging repository, lowering barriers for contributions and enabling real-world usage before final inclusion in Swift.