Hi again! Am Do., 30. Juli 2026 um 00:33 Uhr schrieb Simon Jakobi <simon.jakobi@gmail.com>:
In other news, Anthropic has generously accepted my application for their open source program (https://claude.com/contact-sales/claude-for-oss), so for the next 6 months, I do have a decent amount of usage that I can spend on reviews (including access to Fable 5!).
Just to prevent any confusion about this: I didn't apply for this program specifically for GlaHiCo (and in fact I applied before my idea for this service was fully formed). I mainly wanted to get free access to some good models, and used my maintainership of unordered-containers with its many reverse dependencies as the primary argument on why I should be accepted. While I do think that catching bugs in GHC is a good use of my free Claude plan, there's no endorsement or anything like this from Anthropic. Apart from this I think that GlaHiCo is ready for some trial runs, so please let me know if there is an MR that I should run it on. By default, I will deliver the report as a snippet in the GlaHiCo repo and a link in a comment below your request. If you have a different preference on this, I will try to accomodate you. If you have any special requests regarding models, prompts etc, just let me know, and I'll try to accomodate them too. Also please note that for now, GlaHiCo is made for a "high-trust" environment. If you want to experiment with prompt injections or anything like that, please run it on your own machine and your own LLM plan, at your own risk. Cheers, Simon
Consequently, I have started vibe-coding a primitive "mini-sashiko" for GHC: GlaHiCo (https://gitlab.haskell.org/sjakobi/GlaHiCo/-/merge_requests/1). Right now there's just a single "finder" agent, and each finding gets checked separately by a "verifier" agent.
The code is a mess already of course, but it's slowly getting useful too. If you have a feature request or want to contribute in other ways, please let me know! :)
Cheers, Simon
Am Mo., 27. Juli 2026 um 19:38 Uhr schrieb Simon Jakobi <simon.jakobi@gmail.com>:
Hi devs!
Inspired by the recent discussion on the LLM policy, I'd like to try introducing LLM-generated code reviews in GHC, as an opt-in service.
My motivation:
* Catch issues before human reviewers spend time on them. * Reduce the number of bugs merged.
What this is — and what it isn't --------------------------------
This is tool output: requested on the MR, produced by a model, posted verbatim and clearly marked as machine-generated. This is not a review in the sense of draft LLM policy.
I'm not vouching for any of it. Think of it as a linter the author could have run themselves, except on my LLM budget. Nobody is required to act on it even read it.
I mention this explicitly because the policy asks reviewers to take full responsibility for each line of their review. I can't do that here — it would mean checking every finding myself, which defeats the purpose and would restrict the service to areas of the compiler I already know well.
How to request one ------------------
* Ping me on the MR with a comment like "@sjakobi llm-review please". * Feel free to request particular aspects the review should cover. * Authors can request a review for their own MRs. Maintainers can request one on any MR. * If I have enough usage left on my plan, I'll confirm that I'm on it. * I'll then prompt the model, and post the result on the MR. * Feedback on the quality of the review is of course very welcome.
What I promise --------------
* Every review is labelled as machine-generated, with model, effort level and the exact prompt used. * Reviews are posted verbatim. I don't edit or curate them, so what you see is exactly what the model produced. * Only the public MR diff and public repository context go to the model. Nothing else. * I'll keep working on the prompts and the choice of model to improve the signal-to-noise ratio. * If the signal-to-noise ratio stays inacceptably bad, we can simply stop this service.
Review coverage ---------------
I'll probably start with a fairly basic review prompt, primarily aimed at correctness issues.
Possible extensions:
* Documentation consistency: check that documentation stays consistent, including Notes elsewhere that reference the changed code. * Performance: check for performance issues — potentially including checking the -ddump-simpl output for the changed code for unnecessary allocation etc. * Feel free to suggest anything else!
Format ------
Initially a single comment per review. Once we reach a good signal-to-noise ratio, we can consider inline comments on the diff.
Caveats -------
This is a volunteer service I intend to provide in my spare time. If I'm AFK or on vacation, reviews will take longer. If I can't keep up with requests, I will prioritise which MRs I run. I might take a break entirely.
Getting involved ----------------
Is anyone interested in joining this effort? If so we could form a team (@llm-reviewers?), and share prompting techniques, model choices, etc.
If the service turns out to be genuinely useful, we can look into automating it and – if necessary – possible funding.
Cheers, Simon