This was spun off from the comment in #21.

There is a problem with scoping which can be revealed by this snippet:

(set! fib (fn* (n)
               (if (<= n 1)
                   n
                 (+ (fib (- n 1)) (fib (- n 2))))))

(let* (n 0)
  (while (<= n 10)
    (do
        (print (fib n))
        (set! n (+ n 1) true))))

Specifically the "set! n" should update the value of the "n" variable inside the let-scope, but doesn't unless the "true" parameter is added.

There are three scopes here:

• The global scope, shared by everything before we execute code.
• A new scope introduced by the (let*binding.
• A third scope entered when a function body is executed.

There's something not quite right about the effects when the function/let scope overlap.