1 12687dd9 2023-08-04 jrmu ;; The first three lines of this file were inserted by DrScheme. They record metadata
 2 12687dd9 2023-08-04 jrmu ;; about the language level of this file in a form that our tools can easily process.
 3 12687dd9 2023-08-04 jrmu #reader(lib "htdp-advanced-reader.ss" "lang")((modname |35.4|) (read-case-sensitive #t) (teachpacks ((lib "draw.ss" "teachpack" "htdp") (lib "arrow.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #t #t none #f ((lib "draw.ss" "teachpack" "htdp") (lib "arrow.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp")))))
 4 12687dd9 2023-08-04 jrmu ;An address-book (ab) is either
 5 12687dd9 2023-08-04 jrmu ;1. empty or
 6 12687dd9 2023-08-04 jrmu ;2. (cons s (cons n ab)) [(list (list s n)
 7 12687dd9 2023-08-04 jrmu ;                               ab)]
 8 12687dd9 2023-08-04 jrmu ;where s is a symbol, n is a number, and ab is an address-book.
 9 12687dd9 2023-08-04 jrmu 
10 12687dd9 2023-08-04 jrmu (define my-book empty)
11 12687dd9 2023-08-04 jrmu 
12 12687dd9 2023-08-04 jrmu add-to-address-book : symbol number -> void
13 12687dd9 2023-08-04 jrmu 
14 12687dd9 2023-08-04 jrmu (define (add-to-address-book name phone)
15 12687dd9 2023-08-04 jrmu   (set! my-book (cons (list name phone) my-book)))