Jan Kurs made an extensive petitparser for CommonMark with tests and everything... it is not complete but it had support for most common stuff. So the best approach would be two write a visitor on top of this parser to output Pillar document model.
Good to know. I will see if we can ask students to do something we have a lecture that starts first week or we could ask asbath. (why a visitor? you mean that he already has production rules that outputs a tree?).
Stef, would it make sense to name them differently? E.g. "Pillar" is the syntax and "Pier" the model (or some other name). Maybe it could reduce the confusion, and improve the dialog surrounding it. Because people use same word when then mean different things.
I do not have the energy for that. Pharo it is the system or the syntax?