1 665c255d 2023-08-04 jrmu (define (map proc items)
 2 665c255d 2023-08-04 jrmu   (if (null? items)
 3 665c255d 2023-08-04 jrmu       '()
 4 665c255d 2023-08-04 jrmu       (cons (proc (car items))
 5 665c255d 2023-08-04 jrmu 	    (map proc (cdr items)))))
 6 665c255d 2023-08-04 jrmu 
 7 665c255d 2023-08-04 jrmu (define (scale-list items factor)
 8 665c255d 2023-08-04 jrmu   (map (lambda (x) (* x factor))
 9 665c255d 2023-08-04 jrmu        items))
10 665c255d 2023-08-04 jrmu 
11 665c255d 2023-08-04 jrmu ;; Exercise 2.21.  The procedure square-list takes a list of numbers as argument and returns a list of the squares of those numbers.
12 665c255d 2023-08-04 jrmu 
13 665c255d 2023-08-04 jrmu (define (square-list-map nums)
14 665c255d 2023-08-04 jrmu   (map (lambda (x) (* x x)) nums))
15 665c255d 2023-08-04 jrmu 
16 665c255d 2023-08-04 jrmu (define (square-list-recurse nums)
17 665c255d 2023-08-04 jrmu   (if (null? nums)
18 665c255d 2023-08-04 jrmu       '()
19 665c255d 2023-08-04 jrmu       (cons (* (car nums) (car nums))
20 665c255d 2023-08-04 jrmu 	    (square-list-recurse (cdr nums)))))
21 665c255d 2023-08-04 jrmu 
22 665c255d 2023-08-04 jrmu (define (test-case actual expected)
23 665c255d 2023-08-04 jrmu   (load-option 'format)
24 665c255d 2023-08-04 jrmu   (newline)
25 665c255d 2023-08-04 jrmu   (format #t "Actual: ~A Expected: ~A" actual expected))
26 665c255d 2023-08-04 jrmu 
27 665c255d 2023-08-04 jrmu (test-case (square-list-recurse (list 1 2 3 4)) '(1 4 9 16))
28 665c255d 2023-08-04 jrmu (test-case (square-list-map (list 1 2 3 4)) '(1 4 9 16))
29 665c255d 2023-08-04 jrmu