Marpa-HTML is derived from, and replaces Marpa::UrHTML.
For an example of how to output the HTML, look at the html_fmt utility which is part of the Marpa-HTML distribution. Warning: html_fmt is primarily intended to pretty-print HTML for reading. This keeps it pretty simple. I find most of the time the HTML output also renders the same as the input, but you can't rely on that.
I'll look into providing an equivalent to as_HTML(). Transforming a table with zebra striping might be a good example for me to add. I'll also look into that.