1 (define (double p)
2   (lambda (x)
3     (p (p x))))
4 
5 ;; What value is returned by
6 
7 ;; (((double (double double)) inc) 5)
8 nn
9 (((double (double double)) inc) 5)
10 (((double (lambda (x)
11 	    (double (double x)))) inc) 5)
12 (((lambda (y)
13     ((lambda (x)
14        (double (double x)))
15      ((lambda (x)
16 	(double (double x))) y))) inc) 5)
17 (((lambda (y)
18     ((lambda (x)
19        (double (double x)))
20      ((lambda (x)
21 	(double (double x))) y))) inc) 5)
22 (((lambda (x)
23     (double (double x)))
24   ((lambda (x)
25      (double (double x))) inc)) 5)
26 (((lambda (x)
27     (double (double x)))
28   ((double (double inc)))) 5)
29 (((lambda (x)
30     (double (double x)))
31   ((double (double inc)))) 5)
32 (((lambda (x)
33     (double (double x)))
34   ((double (lambda (x)
35 	     (inc (inc x)))))) 5)
36 (((lambda (x)
37     (double (double x)))
38   ((double (lambda (x)
39 	     (inc (inc x)))))) 5)
40 (((lambda (x)
41     (double (double x)))
42   ((double (lambda (x)
43 	     (inc (inc x)))))) 5)
44 
45 ;; Suppose we defined the procedure below as dd
46 ;;(lambda (x)
47 ;;  (double (double x)))
48 (((lambda (x)
49   (dd (dd x))) inc) 5)
50 
51 (((dd (dd inc))) 5)
52 (((dd (double (double inc)))) 5)
53 (((dd (double (lambda (x)
54 		(inc (inc x)))))) 5)
55 (((dd ((lambda (x)
56 		(inc (inc x)))
57        ((lambda (x)
58 	  (inc (inc x))) x)))) 5)
59 ((((double (double ((lambda (x)
60 		(inc (inc x)))
61        ((lambda (x)
62 	  (inc (inc x))) x)))))) 5)