Thank you both for the comprehensive answers. I have started to write a parser for Adelie-like commands, but have noticed that I have much to learn about Lil and its operators. They are crazily powerful, but take some time getting used to.
I should really start with what is there already, so thank you for pointing this out.
@woodring's approach seems a nice next step without having to write a full parser for a command language, so thank you for this.
You might find it useful to take a look at lildoc.lil in the Decker repository. It's a markdown processor and Lil syntax highlighter used for generating all of Decker's documentation.