I dunno, to me that seems like all YAML's mistakes all over again. I quite like the conciseness, and significant whitespace seems like a good match here, but the double hyphen thing really seems odd to me. And the syntax is so hard to parse, apparently, that their own example is syntax highlighted incorrect, coloring content as if it's tags.
If I may ask, what made you settle on the double dash to disambiguate content from tags? Like is it some sort of nod to SGML from way back when? It seems like an odd choice to me at first glance, but I bet it was thought about long and hard so I’d love to hear some background about what alternatives you considered.
I was looking at Marko a few years ago because of the concise syntax. I have always thought highly of Pug and would have loved a framework that integrated that sort of elegant, minimal syntax. Unfortunately, Marko doesn’t even get the syntax highlighting right in its own docs for this style.
The example on that page with leading commas to separate tag attributes, and a number of other choices across the framework are also a turn off for me personally.
I’ve mostly been using Svelte for the past half-decade instead but still hope for something more elegant to come along.
I especially love the pug style concise syntax which for some reason they have buried deep into the docs rather than showcasing front and center.
https://markojs.com/docs/reference/concise-syntax