lfe.io 5.0: Rust Tooling, All the Way Down

If you've ever tried to contribute to lfe.io -- and bless you if you have (for we have sinned) -- you know the toolchain was a bit of mess. Zola for the SSG (that one wasn't too bad). TailwindCSS, which meant npm. Preline, which meant npm. Yarn, which meant npm-but-also-yarn. Docker, because the CI needed a particular Zola pinned next to a particular Node pinned. A Makefile that called docker run to call npx to call... well, you get the idea.

This is the LFE community. We don't do npm. We don't do Node sitting on node_modules/ like a hen on a clutch of malicious eggs. We use Erlang. We use LFE. We use, when the occasion calls for it, Rust. (In fact, we've been publishing books using Rust's mdbook for almost a decade, now.) So when I sat down a few weeks ago to fix the site's perennial "the Tailwind output is stale" problem for the third or fourth time, I decided that what I actually wanted was to never have to type npm again to ship a tweak to the front page.

Today I'm landing lfe.io 5.0, which does exactly that.

What changed

The site still renders the same. Same content, same layout, same dark mode, same code-excerpt tabs on the masthead. If you visit lfe.io right now you won't see a single new pixel. Under the hood, though:

• Zola → Cobalt. Same Rust-ecosystem static site generator family, different design choices. Liquid templates instead of Tera. YAML data files instead of TOML buried-in-front-matter. Out of the box it's a little less featureful than Zola, but it gave us a cleaner surface to build on top of.
• A new build tool: lfesite. A small Rust CLI living at tools/lfesite/ in the repo. It handles data pre-rendering, SCSS compilation (via the grass crate), Tailwind, and Cobalt orchestration. Six subcommands, ~50 tests.
• The npm toolchain is gone. Tailwind is the standalone CLI binary now -- lfesite auto-downloads and caches it on first run. Preline's Tailwind plugin variants are inlined as Tailwind v4 @variant declarations in tailwind/site.css, so we don't need the JS plugin either. No package.json. No node_modules/. No Docker.
• The home page content lives in _data/home/*.yml now. It used to live in a 579-line TOML front-matter block on content/_index.md, which... yeah. Editing the features cards meant editing TOML tables inside a markdown file's front-matter and praying. Now each widget has its own YAML file: features.yml, books.yml, videos.yml, excerpts.yml, and so on. Markdown fields use a _md → _html convention; lfesite prerender handles the rest.

The contributor experience

This is the part I'm most excited about. To build the site now, you need exactly one thing: Rust. That's it. From a fresh clone:

make build

That'll install lfesite, install cobalt, download the Tailwind binary, compile your SCSS, run Tailwind, build the site, and generate the sitemap. No npm install. No Docker pull. No "but it works on my machine."

make serve gives you a dev server with file watching. make help gives you a colorful menu of every other target. make check-tools tells you what's missing.

Numbers

Because it's fun:

The diff against the old Zola-built output came down to 74 identical files plus a handful of cosmetic differences (meta tag formatting and minified-CSS whitespace). Not bad for a ground-up rebuild.

Bug fixes that snuck in along the way

The Download dropdown menu has been broken for about two years. Surprise! It works again. The dark/light theme toggle wasn't actually doing anything (the hs-dark-mode-active variant wasn't registered). Fixed. The tab highlighting on the code-excerpt widget didn't visibly indicate which tab was active. Fixed. A stray </div> in the closing section was prematurely closing a parent container. Gone. The     hack in books.md and community.md that nobody remembers writing? Deleted.

What's next

The site is on Cobalt. The blog is still on its old stack. Cobalt is made for blogs -- collections, RSS, archives, tags, pagination, the works. The next big project is bringing blog.lfe.io over too.

Come find us on Discord or Mastodon if you want to help. The new contributor story is finally one I can say with a straight face: clone the repo, install Rust, type make build. That's the whole onboarding.

No npm. No tears.