Standard Library

The Swift standard library provides the runtime behaviour for all built-in types and protocols. tswift implements these entirely in Rust inside tswift-std. The frontend provides type shapes; tswift-std provides the behaviour.

Legend: ✅ Implemented · 🟡 Partial · ⬜ Missing · 🚫 Out of scope. Member counts are generated by python3 tools/stdlib-inventory/coverage.py --emit-json from the live runtime registry — nothing on this page is hand-typed. Use the search box and status chips below to explore the full member list.

Known divergences

Documented honestly rather than papered over:

• Fitzpatrick skin-tone modifiers — the grapheme segmenter treats emoji + modifier as two Characters (ZWJ families work correctly).
• Unsafe*Pointer family, withUnsafe*, transcode, va-list — not honestly implementable in a tree-walking interpreter; intentionally excluded rather than faked.

What’s next

1. Remaining String members — UTF-8/UTF-16 view APIs, unicodeScalars.
2. Collection conformances for custom types — custom types in for-in, count, index subscripting.
3. AsyncSequence — for await over custom types.

To see how these map to GitHub issues, visit the issue tracker.