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RaTeX: KaTeX-compatible LaTeX rendering engine in pure Rust

188 points · 105 comments · 1 month ago · atilimcetin

ratex.lites.dev

Hendrikto1 month ago
I used LaTeX for approximately 10 years, for little things to relatively complex, including my bachelor’s and master’s theses. It never felt natural at reliable or consistent. Every customization required weird \makeatletter \makeatother hacks and was very brittle. Everything seemed more complicated than necessary and hard to grok, with weird interdependencies and interactions.
There are probably good reasons for all of that, but it is just both bad DX and bad UX. It feels like you need to be a hardcore LaTeX expert or consult with one, in order to accomplish the most mundane things. Especially in a reliable way, that won’t break upon making seemingly unrelated changes, or won’t break other things itself.
I used Typst for a few weeks. It already feels much more understandable, consistent, hackable, and customizable. I guess that is the difference between an ad hoc macro system and an actually thought through programming language.
The only drawback I can see is the ecosystem being smaller and less mature. That is, however, counteracted by being able to do things on your own, without immersing yourself deeply in LaTeX for years. Also, it will improve with time.
LaTeX is great, don’t get me wrong. But its heritage and historical baggage is really dragging it down.
azverev1 month ago
Pixel-diff CI against a golden suite is the right discipline for layout libraries, and it's noticeably rare in the JS ecosystem.
Most "matches KaTeX" claims I've seen in the wild rely on screenshot eyeballing, which collapses on edge cases like spacing primes, integral subscripts, and matrix delimiters that scale.
One thing I'd be curious about: how are font fallbacks handled when the same Rust core ships to platforms with different system font availability?
KaTeX bundles fonts and assumes they load cleanly; CoreGraphics and Skia bring their own glyph caches and metrics.
Does the display list carry metric snapshots from the host text shaper, or does the core compute layout from a bundled metric file independent of the backend?
tabbott1 month ago
It's interesting to me that the page doesn't describe the size of the rust binary (relevant for mobile app use cases where you would need to add the Rust binary to your app) or performance.
The webpage also does read like it was at least heavily LLM assisted, which makes it a bit hard to trust it.
That all said, this is definitely something I'd be interested in using for Zulip if is indeed going to be a well maintained open source project.
(We currently have a node server component that the Zulip server runs only the render LaTeX).
thangalin1 month ago
When developing KeenWrite[1], I opted to support only plain TeX. This is because I wanted math typesetting to work for either LaTeX or ConTeXt[2]. To render TeX in the preview panel, I forked NTS[3] into a highly optimized Java version. The lack of cross-platform event-based UI system is what kept me from writing the entire application in Rust (some ten years ago). Has the Rust ecosystem improved with respect to Markdown processing, event-based UIs, and now TeX support?
[1]: https://keenwrite.com/screenshots.html
[2]: https://wiki.contextgarden.net
[3]: https://ctan.org/tex-archive/systems/nts
xworld211 month ago
I suppose somebody has to ask (and most likely complain) about this: what does RaTeX do for accessibility? I gather that it produces images. I checked the demo, and there's not even an alternative text or an ARIA label, so this seems completely invisible to anybody relying on a screen reader. This is quite a step backwards compared to modern LaTeX, which can now tag equations with MathML within the PDF, or using MathJax, or any other serious tool targeting HTML, like pandoc or LaTeXML.
Is accessibility anywhere on the roadmap for RaTeX?
TheRealPomax1 month ago
I am so confused. There's already a native version of LaTeX... it's... it's LaTeX. Why would a Rust implementation need to match KaTeX instead of properly implementing a real (and modern, so unicode-out-of-the-box) TeX engine, that LaTeX (which is a set of convenience macros) then trivially runs on top of?
eXpl0it3r1 month ago
Despite the "Gold-suite" comparison, when looking at the KaTeX and RaTeX output [1], the KaTeX output is consistently better. RaTeX has either a lot of aliasing going on or appears blurry.
But the native and library nature of RaTeX is very interesting, especially with the provided C ABI.
[1] https://ratex.lites.dev/demo/support-table
nixpulvis1 month ago
I'm not sure how much overlap there is between this project and Tectonic [1], but that's what I use personally for local PDF generation, and it's also using a good bit of Rust.
Just thought I'd mention since it's related and I really like the project.
[1] https://github.com/tectonic-typesetting/tectonic
DominikPeters1 month ago
The landing page (clearly to a large part written by LLM) does not mention that both KaTeX and mathjax can render to SVG in node. This wasm approach might still be lighter, but the advantage is not as clear as the page makes it seem. (It also contains LLM dishonesties like that the bundle size is 0 KB.)
IshKebab1 month ago
I wish it was standard for projects to say the extent to which they were vibe coded, in the same way that they give a license.
Rochus1 month ago
Interesting. Reminds me of Typst (both implemented in Rust and replacing TeX to some degree) and Microtex.
umvi1 month ago
We recently switched from Node.js + Mathjax for rendering latex to Goja (https://github.com/dop251/goja) + Mathjax, and surprisingly it worked really well. We did this because the app is already 99% golang, and this allows us to eliminate the remaining non-go pieces, greatly simplifying the SBOM. And yes, we tried go-latex, but it's not nearly as feature complete as Mathjax. Not to mention using goja + Mathjax adds 10MB to binary size while Node.js adds 200MB+
mrichman1 month ago
I switched to Typst a year ago and never looked back
jedberg1 month ago
I don't know why but this chain amuses me: RaTeX -> KaTeX -> LaTeX.
I guess it shows how everyone loves but hates LaTeX and is always trying to bolt on that one last thing that will make it good.
marvinified1 month ago
Interesting! Would love to see how RaTeX evolves.
Piterniel1 month ago
JS bundle (typical) 0 kB JS (core is WASM)
I guess you should mention how much is WASM, right?
[deleted]
colechristensen1 month ago
Anybody embed it in a markdown renderer yet?
flakiness1 month ago
JS bundle (typical) 0 kB JS (core is WASM)
Hello?
Trolling aside, I found this kind of Rust-powered typeset modernization promising. I used Typst and liked it. This one would have its own niche too.
ceayo1 month ago
I'm sorry but the only thing that truly understands TeX, is, and will forever be, TeX.
danborn261 month ago
A native Rust alternative to KaTeX is a welcome addition. This should make math rendering much easier to integrate into Rust based static site generators.

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