yex

yex is a typesetter. It's built to behave like Donald Knuth's TeX typesetter, and many TeX documents are quite acceptable to yex. But yex is written in Python, and it can easily be extended to do other things.

It won't be useful for typesetting ordinary documents as yet. But I encourage you to help fix bugs.

The biggest issues we're solving are:

• plain.tex does not parse (issue #58). Without this stylesheet, yex is unusable for ordinary work.
• Some controls are still unimplemented (see label).
• Tests should be as rigorous as they can be; in particular, we need tests based on every rule in David Bausum's TeX Primitive Control Sequences. See issue #118.

You can read an overview of the codebase if you're interested in getting involved.