sicp习题试解 (2.21)

; ======================================================================

;

; Structure and Interpretation of Computer Programs

; (trial answer to excercises)

;

; 计算机程序的构造和解释(习题试解)

;

; created: code17 07/27/05

; modified:

; (保持内容完整不变前提下，可以任意转载)

; ======================================================================

;; SICP No.2.21

(require (lib "math.ss"))

(define (square-list-basic items)

(if (null? items)

()

(cons (sqr (car items)) (square-list-basic (cdr items)))))

(define (square-list-with-map items)

(map sqr items))

;; Test-it:

;; Welcome to MzScheme version 209, Copyright (c) 2004 PLT Scheme, Inc.

;; > (define test-data (list 1 2 3 4))

;; > (square-list-basic test-data)

;; (1 4 9 16)

;; > (square-list-with-map test-data)

;; (1 4 9 16)