*** https://github.com/markdoc/markdoc
*** https://github.com/christianvoigt/argdown - Argumentation
*** https://github.com/jgm/djot - JGM designs a simpler Markdown, with an AST
+*** https://github.com/typst/ / https://www.user.tu-berlin.de/laurmaedje/programmable-markup-language-for-typesetting.pdf - technically sound modern LaTeX replacement, but not open source (yet?)
*** Markdown
**** https://github.com/lezer-parser/markdown
**** https://github.com/kivikakk/comrak