The decision to use Zig over Rust for the Bun JavaScript runtime was influenced by several key factors related to performance, compilation speed, and developer experience.
Performance and Memory Management
Zig's manual memory management capabilities are a significant advantage when it comes to performance. Developers noted that Zig allows for more direct control over memory allocation, which can lead to faster execution times. This is particularly beneficial for projects like Bun, which prioritize speed and efficiency. In contrast, Rust's safety features, while beneficial for preventing certain types of errors, can introduce overhead that may slow down performance in specific scenarios[1][2].
Compilation Speed
Another major factor is the compilation speed of Zig compared to Rust. Developers expressed frustration with Rust's longer compilation times, which can hinder productivity. Zig compiles much faster, making it more appealing for rapid development cycles. This speed allows developers to iterate quickly without the downtime associated with lengthy compile processes[1][2][5].
Developer Experience
The overall developer experience with Zig was also highlighted as a reason for its selection. Zig's design philosophy emphasizes simplicity and ease of use, which can lead to a more enjoyable coding experience. Developers found that they could write code in Zig without the complexities often associated with Rust's borrow checker and safety guarantees. This ease of use can be particularly advantageous in projects where performance tuning and low-level programming are crucial[1][3][4].
Comptime Feature
Zig's unique `comptime` feature allows for powerful compile-time computations, which many developers found appealing compared to Rust's macro system. This capability enables more flexible and efficient code generation during the compilation phase, enhancing performance and reducing runtime overhead[1][2].
In summary, the choice of Zig over Rust for Bun was primarily driven by its superior performance characteristics, faster compilation times, and a more straightforward developer experience that aligns well with the project's goals of speed and efficiency.
Citations:[1] https://www.p99conf.io/2023/11/14/bun-tokio-turso-rust-zig/
[2] https://github.com/oven-sh/bun/discussions/994
[3] https://turso.tech/blog/why-i-am-not-yet-ready-to-switch-to-zig-from-rust
[4] https://blog.lohr.dev/after-a-day-of-programming-in-zig
[5] https://news.ycombinator.com/item?id=37447780
[6] https://www.youtube.com/watch?v=CbQVR4v5PZw
[7] https://users.rust-lang.org/t/is-zig-lang-faster-than-rust/70390