Swift 6.4 stabilizes Subprocess and speeds WebAssembly bridging
Developers get a portable API for working with external processes and a faster path between Swift and JavaScript.
Swift 6.4 gives developers a stable, portable way to start and communicate with child processes through the Subprocess package, while also bringing changes to performance, concurrency and tooling. For lower-copy workloads, it adds UniqueArray and related borrowing APIs; asynchronous cleanup can now use await directly in defer without spawning a separate Task. Interoperability includes bridging between C++20 std::span and Swift Span, along with expanded Java support, and JavaScriptKit’s WebAssembly bridge runs up to 40 times faster than dynamic bridging. Swift 6.4 also improves module debugging and makes Swift Build the default across supported platforms.
Why it matters
For developers, Swift 6.4 offers a consistent way to start and communicate with external processes across platforms, along with faster JavaScript bridging in WebAssembly. That gives teams working across Swift and other runtimes a more direct way to connect their code.
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Sources
- InfoQ