Yes, I suppose that's something I've never grown quite used to with lisp - that it's lists (as a special form of "leaning" trees) and trees - not arrays and mat

Yes, I suppose that's something I've never grown quite used to with lisp - that it's lists (as a special form of "leaning" trees) and trees - not arrays and matrices. I suppose even proper lists are incidental - it's really all about trees (and also parse trees).