Bun ditches Zig for Rust with help from Claude Fable 5, writes over a million lines of code in 11 days

Jul 11, 2026

The JavaScript tool Bun has been fully rewritten from Zig to Rust, with Anthropic's Fable 5 AI handling most of the work. The rewrite resulted in over a million lines of code generated in just 11 days.

Why it matters: This showcases the potential of AI to accelerate large-scale software migrations and rewrites.

Full story at: The Decoder ↗