SICP Exercise 2.22

Exercise 2.22.  Louis Reasoner tries to rewrite the first square-list procedure of exercise 2.21 so that it evolves an iterative process:


(define (square-list items)
  (define (iter things answer)
    (if (null? things)
        answer
        (iter (cdr things)
              (cons (square (car things))
                    answer))))
  (iter items nil))

Unfortunately, defining square-list this way produces the answer list in the reverse order of the one desired. Why?
Louis then tries to fix his bug by interchanging the arguments to cons:


(define (square-list items)
  (define (iter things answer)
    (if (null? things)
        answer
        (iter (cdr things)
              (cons answer
                    (square (car things))))))
  (iter items nil))

This doesn't work either. Explain.

SOLUTION


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