What would be an accessible way to generate interactive exercises with TeXmacs?
Numbas (http://numbas.mathcentre.ac.uk/) and WebWork (http://openwebwork.org/) are in my opinion the most advanced solution for this task (without TeXmacs): Both use computer algebra to recognize equivalence of submitted answers like 2*x and 2x.
PreTeXt (http://pretextbook.org/) as an XML-based dialect is rather intended for cross-format publishing of math books, but includes the possiblity to include interactive exercises.
I would be interested in your experiences on this topic.