Gergely Orosz • 7/16/2026

The Pulse: What can we learn from Bun’s rapid Rust rewrite with AI?

This article, from the Pragmatic Engineer Newsletter, explores Bun's decision to rewrite its JavaScript runtime from Zig to Rust, driven by persistent memory safety issues. It details the challenges of mixing garbage-collected and manually-managed memory in Zig, leading to crashes and leaks. The migration leverages Fable, an AI-powered tool, and highlights Rust's safety guarantees. The piece covers technical trade-offs, the impact on Bun's 22M monthly users, and broader lessons for senior engineers on language choice and stability in production systems.

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#JavaScript #rust #Zig