1 665c255d 2023-08-04 jrmu (define (test-case actual expected)
 2 665c255d 2023-08-04 jrmu   (newline)
 3 665c255d 2023-08-04 jrmu   (display "Actual:   ")
 4 665c255d 2023-08-04 jrmu   (display actual)
 5 665c255d 2023-08-04 jrmu   (newline)
 6 665c255d 2023-08-04 jrmu   (display "Expected: ")
 7 665c255d 2023-08-04 jrmu   (display expected)
 8 665c255d 2023-08-04 jrmu   (newline))
 9 665c255d 2023-08-04 jrmu 
10 665c255d 2023-08-04 jrmu (define (accumulate op initial sequence)
11 665c255d 2023-08-04 jrmu   (if (null? sequence)
12 665c255d 2023-08-04 jrmu       initial
13 665c255d 2023-08-04 jrmu       (op (car sequence)
14 665c255d 2023-08-04 jrmu 	  (accumulate op initial (cdr sequence)))))
15 665c255d 2023-08-04 jrmu 
16 665c255d 2023-08-04 jrmu (define (horner-eval x coefficient-sequence)
17 665c255d 2023-08-04 jrmu   (accumulate (lambda (coefficient remaining-horner) 
18 665c255d 2023-08-04 jrmu 		(+ coefficient
19 665c255d 2023-08-04 jrmu 		   (* x remaining-horner)))
20 665c255d 2023-08-04 jrmu 	      0
21 665c255d 2023-08-04 jrmu 	      coefficient-sequence))
22 665c255d 2023-08-04 jrmu 
23 665c255d 2023-08-04 jrmu ;; (test-case (horner-eval 0 '()) 0)
24 665c255d 2023-08-04 jrmu ;; (test-case (horner-eval 10 '()) 0)
25 665c255d 2023-08-04 jrmu ;; (test-case (horner-eval 0 '(1)) 1)
26 665c255d 2023-08-04 jrmu ;; (test-case (horner-eval 2 '(1 3 0 5 0 1)) 79)
27 665c255d 2023-08-04 jrmu ;; (test-case (horner-eval -1 '(2 4 1 1 8 3)) 3)
28 665c255d 2023-08-04 jrmu ;; (test-case (horner-eval 1.23 '(3 5 2 9 4)) 38.079068639999996)
29 665c255d 2023-08-04 jrmu 
30 665c255d 2023-08-04 jrmu ;; Exercise 2.35.  Redefine count-leaves from section 2.2.2 as an accumulation:
31 665c255d 2023-08-04 jrmu 
32 665c255d 2023-08-04 jrmu (define (count-leaves t)
33 665c255d 2023-08-04 jrmu   (accumulate + 0 (map (lambda (subtree)
34 665c255d 2023-08-04 jrmu 			 (cond ((null? subtree) 0)
35 665c255d 2023-08-04 jrmu 			       ((not (pair? subtree)) 1)
36 665c255d 2023-08-04 jrmu 			       (else (count-leaves subtree))))
37 665c255d 2023-08-04 jrmu 		       t)))
38 665c255d 2023-08-04 jrmu 
39 665c255d 2023-08-04 jrmu (test-case (count-leaves '()) 0)
40 665c255d 2023-08-04 jrmu (test-case (count-leaves '(((())) () (() (())))) 0)
41 665c255d 2023-08-04 jrmu (test-case (count-leaves '(2 3 0 9 8)) 5)
42 665c255d 2023-08-04 jrmu (test-case (count-leaves '((2) (1 (2 5 (8 (9) 3) 2)) 4)) 9)