SICP:1.43重复调用函数

#lang racket

(define (repeated f n)
  (define (compare f1 f2)
    (lambda(x)
      (f1 (f2 x)));lambda
    );compare

  (define (doing result n)
    (if (= n 1)
    result
    (doing (compare result f)
           (- n 1))
     );if
    );doing
  (doing f n)
  );repeated

(define (square x)
  (* x x)
  );square

((repeated square 2) 5)

最后结果： 625