> if you cannot control evaluation of forms / expressions

Assuming quote works, you can do:

  (eval (macro-expand '(
  # rest of file goes here
  )))

which I think technically meets the standards for "trivial", albeit annoying.

(Edit: Although it'd have to be eval-with-macro-expand if you want proper first-class macros.)

“Trivial” is the wrong word, but it’s fairly known/common to write an embedded interpreter. The line between interpreting and just plain programming is very blurry in a lisp.

You can still somewhat control evaluation with quote and/or list.