1.43(计算f的n次重复应用)

递归写法:

(define (repeated f n)
  (if (= n 1)
      f
      (compose f
               (repeated f (- n 1)))))

迭代写法:

(define (repeateds f n)
  (define (iter i repeated-f)
    (if (= i 1)
        repeated-f
        (iter (- i 1)
              (compose f repeated-f))))
  (iter n f))