Chapter 2, Building Abstractions with Data
Section - 2.2 - Hierarchical Data and the Closure Property
Exercise 2.47
For the first constructor:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
#lang sicp
(define (make-frame origin edge1 edge2)
(list origin edge1 edge2)
)
(define (origin-frame frame)
(car frame)
)
(define (edge1-frame frame)
(car (cdr frame))
)
(define (edge2-frame frame)
(car (cdr (cdr frame)))
)
Second Constructor:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
#lang sicp
(define (make-frame origin edge1 edge2)
(cons origin (cons edge1 edge2))
)
(define (origin-frame frame)
(car frame)
)
(define (edge1-frame frame)
(car (cdr frame))
)
(define (edge2-frame frame)
(cdr (cdr frame))
)