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.
Quarkdown uses actual functions that return values, they aren't macros.
As for source readability, it's possible to define functions in a separate .qd file and import it via .include {myfile.qd}
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.