lisp syntax variant

I would like to try and create a lisp syntax front-end, both as an exercise to learn a code base a bit and also because I'm impartial to it. I think it's also good exercise to ensure that design can actually accommodate different representations.

Creating this issue as placeholder for related questions / thoughts etc..

The issue names no files, tests, or entry points to begin with. First determine how the existing syntax front-end is structured and whether its design supports another representation, then define the Lisp syntax scope and acceptance criteria before implementing it.

Written by the indexing model from the issue text.