So I kept hearing that the author did this purely because Anthropic wanted a PR story, but reading this entire very well written post, with meticulous detail, what say you now? I never thought it made any sense for him to do this just because Anthropic asked him to. Sometimes you find yourself fighting the stack you're currently using, and another stack (or programming language) looks like it would alleviate a lot. LLM was just another tool in his toolbelt. I had already ported projects that were old and abandoned before using Claude Code, so I knew it was possible.

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nozzlegear 5 hours ago | parent | next [-]

> what say you now?

I think that when you have a $165,000 hammer, all of your problems begin to look a lot like nails.

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giancarlostoro 5 hours ago | parent | next [-]

I've done rewrites like this, maybe it wasn't Zig to Rust, but I have been able to rewrite sizable projects, from C# to Rust before. I incorporated a similar strategy, have Claude Opus review the codebase, write a spec, then have Claude implement it, while reviewing the spec, and using the codebase as fallback and gospel over the spec. That said, it's not the entire story here as I said, there was a lot of thought put into it, it it had not been done with Claude, I have a feeling he might have started an "experimental" version of Bun in Rust instead, as many developers have done in the past before LLMs.

	▲	MindSpunk 3 hours ago \| parent [-]
		Curious why you'd move from C# to Rust. C# has you covered mostly for memory safety so I would guess performance or lots of shared memory across threads?

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benced 5 hours ago | parent | prev [-]

I would guess the cost to do this with humans would be _at least_ $1.5M in compensation alone (I'm thinking three 500k/year Bay Area engineers) so this is already an order of magnitude cheaper.

Is it worth $165K? I'm less sure of that but it's honestly a moot point - this will get to 5 then 4 digits of cost pretty fast.

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BearOso 5 hours ago | parent [-]

I think putting it in terms of API pricing is oversimplifying disingenuously. Anthropic still hasn't pulled the rug out from under us, so I'm sure it cost a great deal of money once everything comes together, likely surpassing 1.5M. Summarily, they got the result faster, which a group of engineers couldn't do, but at a greater expense.

	▲	benced 3 hours ago \| parent \| next [-]
		GLM 5.2 (open-weights) is at or near Opus 4.7 level performance already. I think it's unlikely Anthropic will be able to durably charge us much more than the CapEx depreciation cost of GPUs + the OpEx of running them for non-frontier models (which Fable will be in 6 months to a year).
	▲	3 hours ago \| parent \| prev [-]
		[deleted]

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johnfn 5 hours ago | parent | prev [-]

So much of the discourse around this on HN is nonsensical, and I fully agree with you. It's patently absurd that Anthropic would demand him to rewrite Bun into Rust; it's equally absurd that they would demand any sort of stunt at all when Anthropic already pulled off the biggest stunt with Bun: running Claude Code on it. And why on earth would you cannibalize the runtime of your golden goose?