I feel like we need to heavily differentiate between a rewrite and an AI rewrite.

mebcitto 3 hours ago | parent | next [-]

Not sure it’s so simple. I think close to 100% of new ambitious projects are going to leverage AI at least to some degree. I know a couple that have strict no-AI policies (e.g. Zig), but it’s a tiny minority i think.

So how much AI usage does it make it an “AI rewrite”?

	▲	guenthert 3 hours ago \| parent \| next [-]
		Dunno. I got rather the impression that it's ambitious single-developer projects with no intention of maintenance which leverage those 'AI' code generators the most. Who wants to contribute to an unmaintainable code base?
	▲	Dormeno 3 hours ago \| parent \| prev [-]
		When the majority of the code is written by AI, it is more than 50%.

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maxloh 2 hours ago | parent | prev | next [-]

For instance, the TypeScript rewrite in Go was done mostly by humans and took a year before it was released. That is how you rewrite software that people can trust.

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jatins 3 hours ago | parent | prev | next [-]

rewrites feel like an area where LLMs are better suited than humans imo

It’s mostly grunt work and LLMs are well suited for translation tasks (iirc transformers arch was originally invented for translation)

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satvikpendem 3 hours ago | parent | prev | next [-]

It is more and more the future. No human would want to rewrite one technology to another because it is too marginal a gain. AI on the other hand does not give a shit.

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Zecc 3 hours ago | parent [-]

You underestimate what people are willing to do just for fun.

	▲	dawnerd 3 hours ago \| parent [-]
		Yeah like what do they think the people porting doom to everything possible are thinking?

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mrklol 3 hours ago | parent | prev | next [-]

I agree but I think from Bun we learned that a project with really good tests and enough tokens can be converted from one language to another quite good!

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baq 3 hours ago | parent | prev | next [-]

It’s just a build step now.

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bozdemir 3 hours ago | parent | prev | next [-]

I'd %100 prefer an opus 4.8 rewrite over %99 of the time. Unless Fabrice Bellard is rewriting the stuff I need, I'd prefer AI over a human coder.

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raincole 3 hours ago | parent | next [-]

Or, you know, you can use Postgres. It's right there for you.

	▲	bozdemir 2 hours ago \| parent [-]
		why? if a rewrite is better/faster/secure, why not? (I'm not saying PGrust is better, I didnt even install it, my perspective is in general)

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OtomotO 3 hours ago | parent | prev [-]

AI is an average coder.

It was trained on all code the code that could be found.

Not just code written by genius programmers like Carmack and Bellard.

Given that it's average, I'd prefer a human coder above average :)

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rytill 3 hours ago | parent | next [-]

LLMs learn a distribution during pre-training, not only an average.

Then, by giving them context or by post-training, you can make them sample non-average parts of the distribution they learned.

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OtomotO 2 hours ago | parent [-]

> Then, by giving them context or by post-training, you can make them sample non-average parts of the distribution they learned.

How do you derive that something is "below average" or "average" or "above average"?

	▲	rytill 2 hours ago \| parent \| next [-]
		Well, it’s up to the user or post-trainer of the LLM what they believe to be above average. Then they can design around that. In the case of real world LLMs and post-training, what is above average is defined roughly as: labeled good by expert humans, and scoring high on RL environments related to coding like debugging, passing tests, or running efficiently and verifiably correctly.
	▲	nextaccountic 2 hours ago \| parent \| prev [-]
		> How do you derive that something is "below average" or "average" or "above average"? One technique is RLHF: have an human expert assess it.

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bozdemir an hour ago | parent | prev | next [-]

I dont think Opus 4.8 is an average coder, with my own experience (I have coded 20 + years before even llms existed) it is anything but average. I don't think training data alone determines the success of these models, there are lots of reinforncement learning principles and fine tuning takes place, a crappy code in the dataset doesnt hold those llms scoring high in benchmarks, I dont think an average programmer can score 70% (opus 4.8) in SWE Bench Pro, which is a good one.

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piker 3 hours ago | parent | prev | next [-]

Which you will necessarily have if they’ve completed a Rust rewrite.

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bigupthewhole 3 hours ago | parent | prev [-]

You haven't been using AI extensively I presume...

I've been programming a long time and considered myself among the top in my domain and AI agents using like GPT 5.5 etc. are much better than me.

	▲	OtomotO 3 hours ago \| parent \| next [-]
		> You haven't been using AI extensively I presume... Ex falso quodlibet > I've been programming a long time and considered myself among the top in my domain I am not trying to attack you, but you considered yourself that... I don't know whether you actually were and frankly I don't care.
	▲	witx 3 hours ago \| parent \| prev [-]
		[flagged]

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egorfine 2 hours ago | parent | prev | next [-]

We already have a well established term for AI rewrites.

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silon42 2 hours ago | parent | prev | next [-]

It's not that... It's a rewrite by project maintainers vs a fork.

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colordrops 3 hours ago | parent | prev | next [-]

Is there any measurable difference in quality between the two, or are you just going on "vibes"? Is there a correlation between the quality of the manually written code and AI generated code driven by the same dev?

Such crude takes only cause unnecessary friction. If you have a black box that spits out code, and you are unable to distinguish the quality between a top tier dev and an AI inside the black box, then the distinction is unnecessary. Most of the code on the internet is already a black box to you. What percentage of code running on your machines have you vetted by who wrote it and code quality?

AI coding isn't going anywhere and will likely end up generating most code going forward so instead of rejecting it outright or arbitrarily categorizing it we need to focus on solid quantitative and qualitative measures of code and functionality regardless of who wrote it.

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queoahfh 3 hours ago | parent | next [-]

Didn't the initial rewrite of Bun into Rust have an ocean of "unsafe" in it, and wasn't it entirely dysfunctional?

	▲	Leynos 2 hours ago \| parent [-]
		Yes, that was the point. It made unsafe behaviour visible in a way that could be addressed. I hadn't heard any reports of it being dysfunctional.

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lenkite 3 hours ago | parent | prev | next [-]

> Is there a correlation between the quality of the manually written code and AI generated code driven by the same dev?

Aren't you making a strawman argument ? AFAIK this project is not made by an official PostgreSQL core developer, so the entire premise of your argument is invalid.

	▲	colordrops 44 minutes ago \| parent [-]
		I phrased that improperly which made you and probably others misunderstand. What I meant is, is the quality of AI generated code correlated with the developer? The answer is yes, a bad dev will absolutely produce worse code using AI than a good developer - the point being that there isn't just one level of quality of code coming out of AI, even with the same model and harness.

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dwedge 3 hours ago | parent | prev [-]

> Is there a correlation between the quality of the manually written code and AI generated code driven by the same dev?

If the dev doesn't vet the code, it doesn't matter how good quality a dev they would be if they wrote the code - they didn't. Sure, the dev would probably drive the initial architecture discussion better and some people are using AI in small batches with tests and vetting everything, but some previously great devs are throwing in PRs that touch hundreds of files at once with one commit.

A lot of people I previously considered great developers have become people I would not recommend for a job in the past 2-3 years.

> If you have a black box that spits out code, and you are unable to distinguish the quality between a top tier dev and an AI inside the black box, then the distinction is unnecessary.

Sure, but this is just begging the question. If nobody could tell, the term 'slop' wouldn't have become so popular.

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colordrops 42 minutes ago | parent [-]

You must be replying to a different comment. Seems completely unrelated to what I wrote. I never claimed that there wasn't AI slop. My point is that there are different levels of code coming out of AI, both due to the quality of the model and harness, and the quality of the engineer that is driving it. Thus you can't just bucket all AI developed code the same.

100% there is slop created by humans and really solid code bases generated by AI driven by a meticulous developer. You are making the exact error I was addressing, which is bucketing all AI code as the same.

	▲	dwedge 11 minutes ago \| parent [-]
		I quote-replied to your comment, so I doubt it was unrelated. > I never claimed that there wasn't AI slop No, but you implied that a top tier dev doesn't produce slop when using AI. > If you have a black box that spits out code, and you are unable to distinguish the quality between a top tier dev and an AI inside the black box My point was that "if" is doing a lot of heavy lifting here and you're coming very close to begging the question. > bucketing all AI code as the same. Most people are not "top tier devs" and over time this will probably become more true. Even if I accepted your premise that "top tier devs" only generate solid code bases with AI, the ease of entry and the ease of spitting out thousands of lines of code means the ratio of bad AI to good AI will not go in a good direction unless it becomes too expensive for non "top tier devs" to use. Given this, I think it's fair to assume AI code is low quality until proven otherwise.

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byzantinegene 2 hours ago | parent | prev [-]

A human rewrite without maintenance is just a hobby project. An AI rewrite is just wasting tokens for god knows what?