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Comment by arrsingh | Hacker News Reader

I don't understand why claude code (and all CLI apps) isn't written in Rust. I started building CLI agents in Go and then moved to Typescript and finally settled on Rust and it was amazing!

I even made it into an open source runtime - https://agent-air.ai.

Maybe I'm just a backend engineer so Rust appeals to me. What am I missing?

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claude code started as an experimental project by boris cherny. when you’re experimenting, you naturally use the language you’re most comfortable with. as the project grew, more people got involved and it evolved from there. codex, on the other hand, was built from the start specifically to compete with claude code. they chose rust early on because they knew it was going to be big.

While the LLM rust experiments I've been running make good use of ADTs, it seems to have trouble understanding lifetimes and when it should be rc/arc-ing.

Perhaps these issues have known solutions? But so far the LLM just clones everything.

So I'm not convinced just using rust for a tool built by an LLM is going to lead to the outcome that you're hoping for.

[Also just in general abstractions in rust feel needlessly complicated by needing to know the size of everything. I've gotten so much milage by just writing what I need without abstraction and then hoping you don't have to do it twice. For something (read: claude code et al) that is kind of new to everyone, I'm not sure that rust is the best target language even when you take the LLM generated nature of the beast out of the equation.]

Think about your question, depending on the tool, Rust might not be needed, is high level memory performance and safety needed in a coding agent ? Probably not.

It's high speed iteration of release ? Might be needed, Interpreted or JIT compiled ? might be needed.

Without knowing all the requirements its just your workspace preference making your decision and not objectively the right tool for the job.

While not directly related to GP, I would guess that a codebase developped with a coding agent (I assume Claude code is used to work on itself) would benefit from a stricter type system (one important point of Rust)

TypeScript is typed.. It's in the name ?

Yes, but if you put type strictness on a line, Rust would be further along I think.

Not to say that Typescript is bad or anything, but I would like to see data on my gut feeling that "stricter languages would make coding agents work better"

This is actually a curious one, I think you might have that gut feeling towards the compiler/transpiler ?

> Yes, but if you put type strictness on a line, Rust would be further along I think.

There are huge differences between build times, as we know, Rust likes to compile with effort, by design, it's important for the compiler to navigate all the nuances. Typescript with bun for example, can run a bit faster. Is the compiler making you think it's more 'type safe' ?

It's that Rust has more rules that allo you to use it's type system to constrain your logic.

Things like borrowing and ownership, having an affine type system, the GADTs, it's more tools in your toolbox to constrain your problem space.

I have a 16GB RAM laptop. It's a beast I bought in 2022.

It's all I need for my work.

RAM on this machine can't be upgraded. No issue when running a few Codex instances.

Claude: forget it.

That's why something like Rust makes a lot of sense.

Even more now, as RAM prices are becoming a concern.

> Claude: forget it.

I don't know what else you're doing but the footprint of Claude is minor.

Anyway my point still stands, you're looking at it as if they are competing languages and one is better at all things. That just not how things work.

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