This makes it very different from Markdown to the point of it not making sense to compare the two, I think. Markdown is not a programming language or a template

This makes it very different from Markdown to the point of it not making sense to compare the two, I think. Markdown is not a programming language or a template language (though people often overlay some sort of template processing after processing the Markdown into HTML in order to apply styles to the resulting HTML, e.g. for many static site generators this is the case...but the Markdown processor has no knowledge of that or concern for it). I feel like this is more much comparable to, as others note, something like Jade/Pug, than Markdown. And, it may be a very good competitor to those sorts of tools, I dunno. Seems like Sundown is a programmers tool; Markdown is an end user tool (often used by programmers in contexts where they don't want to program, like commenting on forums and tickets and such). But, I guess they are all just taking some sort of input and spitting out some HTML. It just seems like Markdown isn't the right thing to compare it to.