sicp 习题2.21

#lang planet neil/sicp;;(square-list (list 1 2 3 4))  =>  (1 4 9 16)(define a (list 1 2 3 4)); define one(define (square x)  (* x x))(define (square-list items)  (if (null? items)      nil      (cons (square (car items)) (square-list (cdr items))))); define two       (define (square-list items)  (map (lambda (x) (* x x)) items))

运行:

Welcome to DrRacket, version 5.3.3 [3m].
Language: planet neil/sicp; memory limit: 512 MB.
> (square-list a)
(mcons 1 (mcons 4 (mcons 9 (mcons 16 '()))))
>