LISP Programming 1062_ex7

http://erdos.csie.ncnu.edu.tw/~klim/scheme/lisp-1062.html

exercise 7: mapping over trees
•Refer to exercise 2.31.

解答:

(define l (list 1 (list 2 3 (list 4 5))))

(define (sq x) (* x x))

(define (tree-map f tree)
  (cond ((null? tree)
          '())
        ((not (pair? tree))
          (f tree))
        (else
          (cons (tree-map f (car tree))
                (tree-map f (cdr tree))))))

執行結果：