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With improvements in coding agents, rewriting code in rust is pretty damn easy, and with a battle tested reference implementation, it should be easy to make som

With improvements in coding agents, rewriting code in rust is pretty damn easy, and with a battle tested reference implementation, it should be easy to make something solid. I wouldn't be surprised if we have full rewrites of everything in rust in the next few years, just because it'll be so easy.

kragen 1y ago
I have had better experiences with LLMs translating code from one language to another than writing code from scratch, but I don't think the current state of LLMs makes it "pretty damn easy" to rewrite code in Rust, especially starting from garbage-collected languages like Perl or Lua. Certainly it's plausible that in the next few years it'll be pretty damn easy, but with the rapid and unpredictable development of AI, it's also plausible that humanity will be extinct or that all current programming languages will be abandoned.
- CuriouslyC 1y ago
  In the last day I've rewritten two service hot cores in rust using agents, and gotten speedups from 4x to >400x (simd+precise memory management) and gotten full equivalent test coverage basically out of the gates from agent rewrites. So I'd say my experience has been overwhelmingly positive, and while I might be ahead of the curve in terms of AI engineering ability, this capability will come to everyone soon with better models/tools.
  - kragen 1y ago
    That's great! What's a service hot core? Which agents are you finding most useful, and what's the best way to take advantage of them? I was recently surprised to see Antirez recommend copying and pasting code back and forth to a "frontier model" instead of using agents: https://antirez.com/news/154 https://antirez.com/news/154
    - CuriouslyC 1y ago
      A service hot core is the part of the service where the vast majority of the computation takes place. I have actually been on a similar workflow with frontier models for a while, but I have an oracle tool that agents can use which basically bundles up a covering set for whatever the agent is working on and feeds it to gemini/gpt5, and generates a highly detailed plan for the agent to follow. It helps a ton with agents derpily exploring code bases, accidentally duplicating functionality, etc. I use claude code mostly because the economics of the plan are unbeatable if you can queue a lot of work efficiently. Most of the agents are pretty good now if you use sonnet, the new deepseek is pretty good too. I have my own agent written in rust which is kicking the pants off stuff in early tests, once I get an adapter to let me use it with the claude code plan in place I'm going to switch over. Once my agent stabilizes and I have a chance to do some optimization runs on my tool/system prompts the plan is to crush SWEbench :P
      - kragen 1y ago
        That's really exciting! Can you run DeepSeek locally?
        CuriouslyC 1y ago
        Maybe if you quantize the everliving hell out of it, but I wouldn't. Depending on how much ram you have I'd run qwen coder, gemma3 or if you can go bigger (huge workstation with research class gpu) I'd go gpt-oss120 or GLM air.
pizlonator 1y ago
I don’t buy it but let’s say that in the best case this happens. Then we’ll have a continuation of the memory safety exploit dumpster fire because these Rust ports tend to use a significant amount of unsafe code. On the other hand, Fil-C has no unsafe escape hatches. Think of Fil-C as the more secure but slower/heavier alternative to Rust
- kragen 1y ago
  Hmm, maybe this should be on the project's homepage: recompiling with Fil-C is a more secure but slower and more-memory-consuming alternative to rewriting in Rust.
  - pizlonator 1y ago
    I want to write a detailed post about the strength of Fil-C’s memory safety guarantee at some point. I haven’t yet thought of a sufficiently precise way and sufficiently classy way to say it.
    - kragen 1y ago
      Does Epic upper management have an opinion?
- CuriouslyC 1y ago
  By default you are right. However you can use static analysis and tooling guardrails to reject certain classes of unsafe code automatically, and force the agent to go back to the drawing board. It might take a few tries and a tiny amount of massaging but I don't doubt it'd get there.
  - pizlonator 1y ago
    If you could get there that way with Rust’s unsafe blocks then you could get there that way with C++
    - 1y ago

kragen 1y ago

I have had better experiences with LLMs translating code from one language to another than writing code from scratch, but I don't think the current state of LLMs makes it "pretty damn easy" to rewrite code in Rust, especially starting from garbage-collected languages like Perl or Lua. Certainly it's plausible that in the next few years it'll be pretty damn easy, but with the rapid and unpredictable development of AI, it's also plausible that humanity will be extinct or that all current programming languages will be abandoned.

CuriouslyC 1y ago
In the last day I've rewritten two service hot cores in rust using agents, and gotten speedups from 4x to >400x (simd+precise memory management) and gotten full equivalent test coverage basically out of the gates from agent rewrites. So I'd say my experience has been overwhelmingly positive, and while I might be ahead of the curve in terms of AI engineering ability, this capability will come to everyone soon with better models/tools.
- kragen 1y ago
  That's great! What's a service hot core? Which agents are you finding most useful, and what's the best way to take advantage of them? I was recently surprised to see Antirez recommend copying and pasting code back and forth to a "frontier model" instead of using agents: https://antirez.com/news/154 https://antirez.com/news/154
  - CuriouslyC 1y ago
    A service hot core is the part of the service where the vast majority of the computation takes place. I have actually been on a similar workflow with frontier models for a while, but I have an oracle tool that agents can use which basically bundles up a covering set for whatever the agent is working on and feeds it to gemini/gpt5, and generates a highly detailed plan for the agent to follow. It helps a ton with agents derpily exploring code bases, accidentally duplicating functionality, etc. I use claude code mostly because the economics of the plan are unbeatable if you can queue a lot of work efficiently. Most of the agents are pretty good now if you use sonnet, the new deepseek is pretty good too. I have my own agent written in rust which is kicking the pants off stuff in early tests, once I get an adapter to let me use it with the claude code plan in place I'm going to switch over. Once my agent stabilizes and I have a chance to do some optimization runs on my tool/system prompts the plan is to crush SWEbench :P
    - kragen 1y ago
      That's really exciting! Can you run DeepSeek locally?
      - CuriouslyC 1y ago
        Maybe if you quantize the everliving hell out of it, but I wouldn't. Depending on how much ram you have I'd run qwen coder, gemma3 or if you can go bigger (huge workstation with research class gpu) I'd go gpt-oss120 or GLM air.

pizlonator 1y ago

I don’t buy it but let’s say that in the best case this happens. Then we’ll have a continuation of the memory safety exploit dumpster fire because these Rust ports tend to use a significant amount of unsafe code. On the other hand, Fil-C has no unsafe escape hatches. Think of Fil-C as the more secure but slower/heavier alternative to Rust

kragen 1y ago
Hmm, maybe this should be on the project's homepage: recompiling with Fil-C is a more secure but slower and more-memory-consuming alternative to rewriting in Rust.
- pizlonator 1y ago
  I want to write a detailed post about the strength of Fil-C’s memory safety guarantee at some point. I haven’t yet thought of a sufficiently precise way and sufficiently classy way to say it.
  - kragen 1y ago
    Does Epic upper management have an opinion?
CuriouslyC 1y ago
By default you are right. However you can use static analysis and tooling guardrails to reject certain classes of unsafe code automatically, and force the agent to go back to the drawing board. It might take a few tries and a tiny amount of massaging but I don't doubt it'd get there.
- pizlonator 1y ago
  If you could get there that way with Rust’s unsafe blocks then you could get there that way with C++
  - 1y ago