Thanks for the feedback. It’s really valuable to get different perspectives as I’m developing the grammar, and I really appreciate it.
My goal with putting everything under the backslash was to avoid having to escape any other character. I kind of deviated from that with allowing Markdownesque formatting for headers and lists, but it’s only necessary to escape these if you want to place a literal ! or . at the beginning of a line. So, generally, as is, the backslash is the only thing you have to worry about escaping.
In the context of the prose text, I don’t think there is any need for standard escape sequences (e.g. for whitespace), since formatting is provided by other means (styles/stylesheets). (In the context of string literals, I’m planning to have the escape sequences work as usual.)
I didn’t mention in my post above, but using triple-colon instead of colon starts a preformatted indented block, so it’s pretty easy to insert code samples in a document.
LaTeX, for example, uses backslash like this prolifically. I’m curious, have you run into a problem with that kind of feature?
I debated the # for comments. I definitely waffled on that one. I agree it’s kind of ugly. And I agree commenting is very common, and much more so than using pound. But HTML drives me crazy with having to escape lt, gt, and ampersand. I don’t use them very often (unless talking about HTML), but for me, this is almost always an oversight that requires a correction cycle. The low frequency of use actually causes the problem for me. So I guess I’m trying to avoid having syntactic gotchas at the expense of having to type an extra character. But I’m still debating this one. There are definitely some issues with it. For example, what if there is a comment inside of the markup? Should that have a backslash in front of the pound too, or omit it since it’s already markup?
As an aside, I did debate using pound for headers and backslash-pound for comments, and decided that THAT was REALLY ugly, and opted for exclamation for headings to avoid confusion.
I didn’t understand the “1.5 character key” terminology you used. Do you have a reference for that terminology?