Pele – Mermaid diagrams as themeable SVG | Hacker News Reader

Pele – Mermaid diagrams as themeable SVG

pele.run

597 pointsdchest63 comments

Anytime I try mermaid for anything more complex than a toy diagram I always end up absolutely frustrated by the arcane and topologically poor layout that is produced.

Styling seems like a trivial problem by comparison.

Graph layout is a famously hard problem!

I wonder if it is almost like writing. In that to make the diagram that communicates well you need to have solved the problem properly.

A common layout implementation is to provide constraints to a SAT Solver… so you were close :)

To my taste, most automatic layout implementations produce horrible layouts. Yes, you can use SAT-solve and optimize your way towards a node ordering that produces no crossing lines, but those rarely create something that makes intuitive sense of the content

Good layout is a lot more like writing, in that you have to think about how the intended recipient will perceive and what you want them to notice in which order, and how to make it easy to follow the various relationships

I have had good luck with D2 and elk or dagre. If you get into the nitty gritty of elk you can do a _lot_ with it.

The tala layout engine for d2 is now included it provides a very good layout.

If only it had a good documentation. I really like the elkjs JavaScript version (thanks, Ulf!) bitte unfortunately transcoding makes transferring the Java docs even harder...

I strongly agree, and that's why I designed Pele to only follow its syntax not its layout. See the examples https://pele.run/examples

The playground also has a Compare mode https://pele.run/playground

Could you not make Pele part of Marmaid or they wont accept a contribution like this?

To quote another reply regarding mermaid by @kepano:

> Mermaid.js has transitioned to "mermaid.ai" and is losing its original vision. Take a look at their new site.

> The latest version of Mermaid (12.1) ships with yet another layout engine (three now), and has a questionable safety record (see CVEs). In Obsidian 1.13 we had to introduce a new toggle/warning because of potential unsafe Mermaid diagrams.

https://x.com/kepano/status/2111575190081847776

The layout quality is very impressive!

Have you given much thought to diffing diagrams? The source can be version controlled and a source diff can be seen, but a visual diff would be amazing and easily sway me from writing prose to writing diagrams.

I've tested a couple of diagrams that I found on some website and I couldn't see any major differences in the layout. Can you point to some systematic differences?

FYI, first two examples are identical here: https://pele.run/examples/timeline

Edit: So is #7 (and almost #8), #9, 10, 11, 12 are identical as well

This is so so awesome! I always find Mermaid hard to read but Pele is a delight. Just sponsored you on Github as a small way of saying thanks for Pele. Thank you so much kepano

I kinda just shove what I want out of it to literally any basic model from the frontier labs, I usually dont need anything super fancy, but it does the job, even color coded regions for me (which is fancier than I usually do) and then I can shove that into Lucid since it can render them.

I have the same issue. A neat trick is to have it so the large language model creates an HTML file with what you need inside of it too. That allows for even more flexibility.

I don't even bother writing mermaid by hand when I'm making decision trees. Instead of visualizing it using PrecisionTree in excel (I just use that for the actual data modeling), I've been first modeling the tree in plaintext, then pipe it through claude with a previous tree I've made as reference. I then ask it to use the content of the current tree and match it to the style of the previous one.

Then you may like tool I use https://ferroman.github.io/diagc/

I like TikZ for this.

I found I had better results with D2, sadly not as ubiquitous as Mermaid.

Indeed. I still can't bring myself to appreciate Mermaid even with Pele.

Is pele open source?

I tried to find the source code of it but I was unable in finding so

Edit: found it, https://github.com/obsidianmd/pele

Also folks, this is a good reminder to please have a github icon on the top of the page to easily show git/github links if the app is open source, also helps in the fact that I can star your projects and bookmark them more easily :-D

Looks like https://github.com/obsidianmd/pele maybe?

I've switched to D2Lang for its easier syntax and the fact Mermaid is hard pushing AI. Appreciate it, Kepano, for making Mermaid a bit more palatable!

[1]: https://d2lang.com/

> A flowchart subgraph keeps its own direction even when it links to nodes outside the subgraph.

This, in and of itself, is sufficient reason for me to switch, even if it were slower than Mermaid.js.

I’ve not even made it through the list yet and I’m sold.

Based on the learning science principles expressed in a recent video from Benjamin Keep, I've been experimenting more often with Mermaid lately in my Obsidian vault. While I know Obsidian has its own canvas plugin, it's obviously much less time consuming to use a markup language to illustrate a network.

And since LLMs are effective at writing reference guides and Mermaid markup from provided context, I've also been experimenting with prompt templates intended to leverage the learning science ideas for connecting concepts using Mermaid.

I'm excited to try out more experiments once Pele is available in Obsidian.

[1] Benjamin Keep video: https://youtu.be/ytXWBHIXLp0

[2] Latest template (from Argon mid): https://rentry.co/xiiw52od

Thank you very much for this!

I use a build script for my static website that renders markdown files into HTML files and swaps out any mermaid codeblocks with rendered SVGs. I used mermaidjs for this but it is very heavy for this purpose (needs an entire chromium instance for the rendering).

This seemed like a perfect fit for my use case and I already swapped it in. I noticed that the layouts were not 1 to 1, but to my pleasant surprise I actually liked the ones Pele renders better than mermaidjs.

Brazilian me thought it was an homage to Pelé. I’m glad the text explains the name.

I'm not Brazilian but i grew up in a world where EVERYONE knew who Pele is (maybe i'm a little old?)...So, i also thought the same, that this was named after him! :-)

Amazing. I just migrated the diagrams on the docs site of a project of mine, and they just look great[0]. Before, I had a combination of mermaid, panzoom, and some minor workarounds to get integrated styling and dark theme work right. Pele not only takes care of all of that, but also manages a nicer layout!

[0] https://cetacean.mazetti.me/authentication#oidc

That looks great. I like theming and controls you added to make it feel native to your site.

Does the official Mermaid library still require a full or headless browser environment in order to lay out the SVG? If so, Pele is great news for embedding Mermaid rendering in other places.

The python mermaidx library works for this, which works well for generating documentation with embedded diagrams as part of CI/CD but the layout/rendering can sometimes be very wonky. For instance I will have a bunch of connections crossing over each other instead of neatly arranged to avoid it. Changing the layout settings does not fix it so sometimes I will just export it from mmdc and embed a png.

There is also Merman on Github that outputs a SVG.

https://github.com/Latias94/merman

Very nice, bookmarked. I built something similar as an Astro plugin using svgdom: https://better-static-sites.github.io/build-tools/mermaid/

It still boggles my mind that mermaid's devs think you need an entire freakin' browser to render an SVG. Sometimes I think people need to be reminded of the fundamentals.

That project is just Claude run rampant. Actually attempt to read this:

https://github.com/Latias94/merman/tree/83e3ea74bf4da30089a8...

This was pretty inspiring -- I have been working on file format rendering for a pager in terminal+browser and totally forgot about Mermaid!

Much of the work uses SVG as an intermediary so this Pele pattern works great. OP is a TypeScript project, seems great for that ecosystem.

Searching found this go-mermaid library [1] that operates similarly with SVG its target. We have a Golang TUI picture/SVG widget and a Golang WASM/browser embedder, so I just forked it and had an LLM add a live Mermaid/SVG demo using them [2]. The demo is intended for go-mermaid so it uses its rasterizer, composited to our widget.

(took <15 minutes since I had worked similarly just days ago and had the components at the ready, plus could point at Pele; these LLMs are ridiculous at forging from patterns)

Cool thing is that same visual experience can be had in a terminal if it supports Kitty graphics protocol.

[1] https://github.com/zkrebbekx/go-mermaid

[2] https://neomantra.github.io/go-mermaid/

Just FYI, "pele" is "mouse" in Latvian. :)

and "skin" in portuguese :)

and a football player in brazil :D

and "d*ck" in slovak...

Spade in French

No meaning in german

It's also the Hawaiian goddess of fire.

Only with an accent on the final é.

Nice work...will try to incorporate it in our tools and projects. Dark mode support is a good highlight. I appreciate this work. Please keep it up.

Thank goodness. Theming mermaid and using it server side is such a nightmare. I had many issues trying to get it to work competently with CSS variables for dark mode / light dark. This seems way better.

I like the approach of rendering directly to SVG, which is what I want -- running layout once and caching the result in the browser or on the server side.

longtime user of GraphViz for that kind of use case but I have a TODO to try programmatic generation of my next software diagram in Inkscape's XML format.

Noting that the mermaid preview in the playground is broken.

Broken in what way? It works for me. Do you have any details? Browser, errors, etc?

Here are the details, sorry for not attaching before https://gist.github.com/kinduff/7eb14bf348fdec4e664b59e758d1...

Thanks! Investigating...

The examples are not very dark-mode friendly

FOUC in the big 26 is crazy work

Blatant self promotion: But if you'd like your Mermaid diagrams rendered in pretty isometric 3D, we've added Mermaid support to Arcentry lately: https://arcentry.com/blog/isometric-mermaid-diagrams-with-ar...

Tools like this are so amazing because they allow Claude to edit and draw and save to a single markdown file. So practical! Version control friendly. People can use them, sure. Buy AI can really take off with tools like this.

Reply on news.ycombinator.com