Buz – A fork of Bun using modern Zig, with sub-1s incremental builds

Original Article ↗ Hacker News Discussion ↗

A new project called Buz aims to be a drop-in replacement for the Bun JavaScript runtime, rebuilding Bun’s pre-Rust codebase in modern Zig to achieve sub‑second incremental builds and cleaner architecture. Commenters debate whether Bun has become “AI slop,” noting reports of 600k lines of messy code and 11k lines of trivially dead code, and argue over whether large-scale “deslopification” with LLMs is realistic or ironic. The thread widens into questions about the future of open-source runtimes (Node, Deno, Bun), the trade-offs between all‑in‑one tooling and modular stacks, and how AI-generated code is reshaping software development practices.

Project Overview & Goals

  • Buz is a fork of pre-Rust Bun, rewritten on “modern Zig” with sub‑second incremental builds.
  • The maintainer is aggressively cleaning up the inherited codebase, removing dead code and relying more on Zig’s stdlib.
  • Early policy: no human-coded contributions until the code is in a “sane” state; LLMs are used heavily to refactor and “deslop” the code.

AI, “Slop”, and Code Quality

  • Some see Bun (especially the Rust rewrite) as emblematic of “AI slop”: large, messy, LLM-driven code that’s hard to maintain.
  • Others strongly reject that label, arguing Bun’s Rust port improves safety via the borrow checker and is not inherently low quality.
  • Many comments note the irony of using LLMs to clean up code that LLMs helped create, but several report practical success when LLMs are tightly steered and verified with tooling.

Ecosystem, Sustainability, and Alternatives

  • Skepticism that Buz can be maintained long term without a strong ecosystem; many expect most users to stick with Bun or revert to Node.
  • Deno is mentioned as another modern runtime, but some worry about its momentum and company stability.
  • Several argue choosing a runtime mainly for its “all-in-one” tooling (like Bun) is risky; Node + specialized tools is seen as good enough by many.

Build Times, Zig, and Rust Rewrite Debate

  • Buz’s sub‑1s incremental builds are cited as proof that fast builds were always possible with Zig and better practices.
  • This is contrasted with Bun’s earlier complaints about Zig compile times and a controversial fork of the Zig compiler.
  • Some view the move from Zig to Rust as partly political and ecosystem-driven; others emphasize Rust’s memory safety guarantees.

Dead Code & Maintenance

  • Buz claims to have removed ~11K lines of trivially dead code from Bun’s ~600K‑line base.
  • Some find this astonishing; others say 1–2% dead code is normal in large, fast-moving projects.
  • LLM-generated code is suspected of contributing to unused, uncleaned branches and utilities.

Meta: JS Tooling & AI Fatigue

  • Multiple commenters express fatigue with endless new JS runtimes/frameworks and AI-generated “solutions” in search of problems.
  • Others still value Bun/Buz for consolidating many tools into one fast runtime, akin to an opinionated, batteries-included framework.