It's not the parentheses or the Polish notation that matter. Those are covered in the first chapter of any Lisp/Scheme book and they are trivial, especially wi

It's not the parentheses or the Polish notation that matter. Those are covered in the first chapter of any Lisp/Scheme book and they are trivial, especially with a proper editor that understands structure and will indent unambiguously accordingly. Unless you're stuck on simple editors like Notepad or Nano, there's no issue here. What's more challenging in Scheme, as Abelson and Sussman teach it, is the use of recursion instead of looping and in particular understanding that recursion is only equivalent to looping when the recursion is in "tail position", i.e. when there is nothing left for the calling function to do except return to its own caller. Common Lisp style tends to use looping, not recursion.