Without commenting on Bun itself as a project, or the nature of the rewrite, it can't be good for Zig that a naive rewrite away from it fixed memory leaks, improved stability, shrunk binary size by 20%, and improved performance by 5%.
True, but rewrites often allow for this sort of benefit in themselves. It's possible rewriting it in zig would have yielded some of the same improvements.
Where is the cost breakdown? I feel like this would be the easiest number to determine and write in this post. It's hard to believe that there have been no problems/downsides since the port.
> Pre-merge, this took 5.9 billion uncached input tokens, 690 million output tokens, and 72 billion cached input token reads — around $165,000 at API pricing
> It's hard to believe that there have been no problems/downsides since the port.
One thing that I found interesting is that most of the discourse surrounding the topic happened with the assumption that the rewrite was happening with an Opus-like model, and not with Fable. Those assumptions, at least partially, were used as arguments against the fact that the rewrite was feasible and/or a good idea.
Clearly the model itself doesn't completely change the narrative, but at least as a note to myself, I would like to be more careful with assuming the capabilities of the models used internally by Anthropic and affiliated orgs.
Adding bespoke animations via Claude Code to the blog post is definitely thematic. It's unclear if they're useful data visualizations as they take a bit of time to parse, but they're neat.
As expected [0] [1], this was a clear advertisement / marketing opportunity of Anthropic's Fable model on rewriting Bun (which powers Claude Code) from Zig into Rust.
Something that would have taken hundreds of developers now took 1 developer with Fable.
Now Claude, rewrite Claude Code from TypeScript to Rust. Make absolutely zero mistakes.
EDIT: the parent has effectively deleted their original comment
> There are a lot of ways to do a terrible job of this. For example, prompting Claude "Rewrite Bun in Rust. Don't make any mistakes." and then praying it would work is not what I did.
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