Bun 用 Claude Fable 5 将代码从 Zig 重写为 Rust，11 天写出超百万行

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

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JavaScript 工具 Bun 已从 Zig 完全重写为 Rust，重写工作主要由 Anthropic 的 Fable 5 完成。开发者 Jarred Sumner 表示，Zig 持续产生难以彻底修复的内存错误和崩溃，而 Rust 能在编译时捕获许多此类 bug。Sumner 使用了预发布版 Claude Fable 5，并行运行约 64 个 Claude 实例，耗时 11 天写出超百万行代码，API 费用约 16.5 万美元。据估算，人类团队完成同样工作需约一年。新版本 Bun v1.4.0 以 canary 版本发布，修复了 128 个 bug，运行速度提升约 2% 至 5%。Bun 团队已于 2025 年 12 月被 Anthropic 收购。

正文 · 原文

The JavaScript tool Bun has been fully rewritten from Zig to Rust, and Anthropic's Fable 5 did most of the work. Developer Jarred Sumner says the switch came down to reliability. Zig kept producing memory errors and crashes that were hard to fix for good. Rust catches many of those bugs at compile time.

Sumner used a pre-release version of Claude Fable 5 for the project. About 64 Claude instances ran in parallel for 11 days, writing over a million lines of code. The API bill came to roughly $165,000. A human team would have needed about a year, according to Sumner. The new version, Bun v1.4.0, is available as a canary release. It fixes 128 bugs and runs about 2 to 5 percent faster. Sumner didn't have to worry about the hefty price tag. Bun and his team were acquired by Anthropic in December 2025.