Yet another Hacker News

Show HN: OmniDiff – Opensource, super fast, content aware Git difftool, in Rust

14 points FabCH 3 hours ago 15 comments

I have been researching what the ultimate diff tool would look like, based on actual diffs in open source repositories.

OmniDiff can diff: code (25 languages), config, images, PDFs, archives, cursors, fonts...

It's fast. It can diff C++ files of tens of thousands of lines in under 100ms, on a 2023 ThinkPad T14s.

It's open source. AGPLv3.

It's based on real diffs. I looked at the 7400 repositories that are listed in Gentoo packages, sampled 2000 diffs and solved them manually to get a good understanding of what is needed, before putting together the diff pipelines for each content type. Incidentally, this also forms the basis of the CI pipeline, so the robustness of the codebase is quite high.

I'm still developing it. It's v0.3.0 at this time. But I have been using it daily as my git difftool for months now, and it works well.

AI Disclosure: Yes, I do use AI. No, I do not vibecode.

paaloeye 2 hours ago | parent

How is it better or worse compared to https://github.com/dandavison/delta ?

FabCH 2 hours ago | parent

It’s much much better with moved code.

Delta adds color to the standard git diff algorithm.

Omnidiff uses a completely different algorithm.

About a third of diffs are significantly better.

paaloeye 2 hours ago | parent

Okay, I'll give it a try then.

paaloeye 2 hours ago | parent

Older submission: https://news.ycombinator.com/item?id=49891989

FabCH 2 hours ago | parent

Not quite.

In the meantime, I added support for all other non-code file formats. Hence the name change.

It’s quite a big chunk of functionality.

anilgulecha 1 hour ago | parent

You have a good core idea here. You're pretty much killing your project in infancy with the AGPL+donation license model. Meanwhile, some other projects will take the core idea of "language aware differ" and release BSD, and one of those will win, including perhaps making it into git/future version controls.

IMO, you should seek to make this a standard that wins, and hopefully other opportunities that come will be where you make commercial hay. My unsolicited 2c.

FabCH 57 minutes ago | parent

I really do care about copyleft and AGPL. It’s a political choice. I specifically chose it because I know from direct experience that big tech is allergic to it.

I actually don’t care about the commercial license. It’s more of an experiment for my own amusement than an actual attempt at building a commercial project.

If it inspires someone to build another one and we still end up with a better differ, I’m ok with that world. As long as the open source community has a better differ.

Note that there already are at least 3 that I am aware of. But they do perform worse on speed and accuracy.

ipsi 50 minutes ago | parent

FWIW, there's probably no point in using a copyleft licence if AI is involved[1][2], unless you've got pretty solid proof AI only "assisted" rather than doing the bulk of the work. Otherwise, you don't have copyright on the generated code, and without copyright the licence is meaningless, AFAIK.

This is not to say you can't or shouldn't use AI, but it's important to understand the tradeoffs you're making.

[1] https://www.scotusblog.com/cases/thaler-v-perlmutter/ [2] https://www.jenner.com/en/news-insights/client-alerts/us-cop...

FabCH 44 minutes ago | parent

I’m not based in the US so SCOTUS doesn’t set meaningful precedent for my IP.

That said, even under those rules, I would be comfortable arguing before the court that this code has significant human involvement and easily passes the copyright standard.

It’s also why I don’t think someone can just easily create another one and license it under BSD. My code is AI assisted, but all truly important pieces were human made.

hebetude 44 minutes ago | parent

Something nobody asked for with licenses nobody wants to use. Project is dead before it started

alexpadula 14 minutes ago | parent

You know hebetube, my mother once said "if you have nothing nice to say: don't say it". You saying those things probably aren't going to make them turn over the license. "Project dead before it started" like who writes those kinds of things over someones work they spent time on. I'd love for you to explain your logic.

cassianoleal 2 minutes ago | parent

> with licenses nobody wants to use

Nobody wants to use AGPL-v3?

https://github.com/ivankovic/omnidiff/blob/main/LICENSE

cocoto 34 minutes ago | parent

How does it compare with diffstatic?

FabCH 26 minutes ago | parent

Comparing is slightly complicated but roughly speaking:

Difftastic only diffs code, which is only 2/3 of all diffs.

When only measured on stuff difftastic supports:

Difftastic is perfect on 64% of diffs and near-perfect on 17% more.

Omnidiff is perfect on 90% of diffs and near-perfect on 5% more.

Speed is

p50 - 35ms difftastic vs 4ms OmniDiff p99 - 637ms vs 420ms

Difftastic wins on license. MIT vs AGPL.

Surac 25 minutes ago | parent

obviously it's in rust. anything the world does not need is in rust