I’ve Given Up on Bun. I’m Removing It from SuperRails

Source: Dev.to

Bun’s implementation language has been migrated from Zig to Rust.

I have no intention of criticizing either Zig or Rust. Both are excellent languages. What I want to criticize is Bun’s development process.

Rust Migration

A recent pull request rewrites Bun in Rust (see GitHub PR #30412). The migration:

• Passes Bun’s pre‑existing test suite on all platforms and fixes several memory leaks and flaky tests.
• Reduces the binary size by 3 – 8 MB.
• Shows benchmark results that are neutral to faster.
• Introduces compiler‑assisted tools for catching and preventing memory bugs, which have previously cost the team a lot of development and debugging time.

The codebase otherwise remains largely the same: the same architecture, the same data structures, few third‑party libraries, and no async Rust.

To try the canary version:

bun upgrade --canary

Note

• Some optimization work is still needed before this lands in a non‑canary version.
• Additional cleanup will arrive in a series of follow‑up PRs.

Diff Overview

The size of the diff is unprecedented. According to reports, the implementation, review, and merge were completed in less than a week using Claude Code. Anthropic, which owns Bun’s developer Oven, may use this “success story” to market Claude models and tools.

Concerns About the Development Process

Even if the migration to Rust resolves the memory‑leak issues and AI‑generated code is of high quality, I am dismayed by a process that releases massive changes almost instantly without thorough review.

• I am not claiming AI‑generated code is evil; it can be useful, and I use it where security risk is low.
• However, I still review generated code repeatedly before trusting it.
• Shipping a large change without taking full responsibility—i.e., without carefully reading and understanding every part of the diff—is unacceptable.

Given the sheer size of this change, it seems physically impossible for the Bun team to have thoroughly reviewed all of it in less than a week. The problem is not the use of AI itself, but the lack of comprehensive review.

Future Plans for My Projects

My products—SuperRails and LazyCafe—depend on Bun. I will be migrating SuperRails from Bun to a pnpm‑based esbuild setup and will consider similar changes for other products, including LazyCafe.

Anthropic and the Bun development team appear focused on short‑term goals: releasing quickly and fixing memory leaks fast. This short‑term focus lacks the perspective needed to keep these tools viable for the long term.

This approach does not align with my development philosophy of quietly running businesses that can survive for decades.

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