Given the PL Theory parts of my question (but seeing it also being part of practical compiler design) Im thinking it might be a better match here than there?
It looks like your question may fit here, but you want to take some time to formulate it appropriately before posting it. In particular, questions strictly on the theory of PL are fine, but any of the practical design questions will fit in much better at StackOverflow.
For a brief history of PL theory on this site, see this thread.
P.S. Also see this piece of our Work-In-Progress-FAQ on which types of questions are appropriate.
Reading the original question, it seems like a question of the form "how might I convert an AST to a control flow graph, and here are formal definitions of ASTs and CFGs in graph notation (or whatever)" would be on scope. The scala aspect appears incidental.