Porting Bun Runtime to Rust: A Deep Dive into Rewriting the Engine

The author documents a project to rewrite the Bun runtime using the Rust language. Bun, originally written in C++, aims to provide a fast JavaScript and TypeScript environment. The rewrite targets Rust’s safety guarantees and modern concurrency features. The article outlines the steps taken to translate core modules into Rust code. Performance benchmarks are compared between the original and the Rust version. Challenges include handling low‑level system calls and preserving API compatibility. The author reflects on the learning curve and community feedback received. Future plans involve polishing the Rust implementation and measuring long‑term stability.