Exercise 5.34: Compile the iterative factorial
procedure


(define (factorial n)
  (define (iter product counter)
    (if (> counter n)
        product
        (iter (* counter product)
              (+ counter 1))))
  (iter 1 1))

Annotate the resulting code, showing the essential difference between the code
for iterative and recursive versions of factorial that makes one process
build up stack space and the other run in constant stack space.