When a Windows write source is registered before a read source on the same handle, _dispatch_muxnote_create() stores EVFILT_WRITE, but _dispatch_unote_muxnote_find() canonicalizes both filters to E...

A source-level look at how Swift Collections implements Deque with circular storage, copy-on-write value semantics, and familiar integer indexing.

Notable changes this month: JavaScriptKit 0.60.0 made Swift-to-JavaScript string bridging faster, and 0.61.0 added opt-in yielding to keep the host responsive; WasmKit 0.4.2 added the multi-memory pro...

Swift is a general-purpose programming language built using a modern approach to safety, performance, and software design patterns.

Use Swift for case to select matching values during iteration, bind associated data, and add precise where conditions without hiding the loop's intent.

Match one Swift enum case, bind its associated values, add conditions, and decide when guard case or an exhaustive switch is clearer.

A source-level look at how Swift Argument Parser turns property wrappers and command types into parsing rules, validation, usage, and help.

How swift-algorithms models overlapping collection slices with paired indexes.

Hello, Swift community! The review of SE-0560: Build configuration conditionals for target dependencies begins now and runs through November 11, 2026. Reviews are an important part of the Swift evolution process. All review feedback should be either on this forum thread or, if you would like to keep your feedback private, directly to me as the review manager by email or DM. When contacting the review manager directly, please put "SE-0560" in the subject line. What goes into a review? The goal...

Announcing Swift 6.4.2 We are happy to announce the release of Swift 6.4.2. Install Swift Toolchain Install via Swiftly swiftly install 6.4.2 or swiftly install latest Download toolchain directly from Install Swift | Swift.org Docker images will be available on hub.docker.com//swift soon (PR) Swift toolchain will be available on WinGet soon (PR) Xcode 27.2 contains Swift 6.4.2 Release Notes Compiler and Optimizer Fixed a miscompile in optimized builds affecting statically initialized arrays...

Hi Swift community, The review of SE-0561: Span-based access to Optional's storage begins now and runs through November 13th, 2026. Reviews are an important part of the Swift evolution process. All review feedback should be either on this forum thread or, if you would like to keep your feedback private, directly to the review manager. When emailing the review manager directly, please keep the proposal link at the top of the message. What goes into a review? The goal of the review process is t...

Motivation It is a common pattern to have a throwing function whose result needs to be bound for use in the enclosing scope. let value = try thrower() // We want to handle any thrown errors and exit early // so that the value binding can stay un-nested. use(value) There are a few ways to achieve this today, none of which are ideal. do/catch The do/catch versions have multiple issues: do { let value = try thrower() use(value) // The happy path is nested } catch { // Error handling...

How AsyncChannel makes Swift producers wait for demand, handles cancellation races, and differs from buffered streams.