My quick take: this is basically just Markdown with LaTeX-style macros, except they're called functions, presumably because at least 1 of them has side effects

My quick take: this is basically just Markdown with LaTeX-style macros, except they're called functions, presumably because at least 1 of them has side effects (the one that defines new functions). I appreciate the syntactic purity of "everything is a function", but the casual integration of structure (html) and styling (css) smells a bit off, but I suppose that line was already blurry anyway. This is cool. I think you'll find a lot of skepticism here for anything that tries to significantly alter markdown. I understand some of the criticism that functions can degrade source readability if overused. Sometimes Turing incompleteness is a virtue. But as far as adding functions to markdown goes, this is probably among the cleanest designs out there.