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 |31.3|) (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 ;A digit is an N >=0 and <=9.
 5 12687dd9 2023-08-04 jrmu 
 6 12687dd9 2023-08-04 jrmu to10 : (listof digits) -> number
 7 12687dd9 2023-08-04 jrmu 
 8 12687dd9 2023-08-04 jrmu Examples:
 9 12687dd9 2023-08-04 jrmu (= (to10 (list 1 0 2)) 
10 12687dd9 2023-08-04 jrmu    102)
11 12687dd9 2023-08-04 jrmu 
12 12687dd9 2023-08-04 jrmu (= (to10 (list 2 1))
13 12687dd9 2023-08-04 jrmu    21)
14 12687dd9 2023-08-04 jrmu 
15 12687dd9 2023-08-04 jrmu (define (to10 alod0)
16 12687dd9 2023-08-04 jrmu   (local ;; accu represents the accumulator
17 12687dd9 2023-08-04 jrmu     ((define (to10-accu alod1 accu)
18 12687dd9 2023-08-04 jrmu        (cond
19 12687dd9 2023-08-04 jrmu          [(empty? alod1) 0]
20 12687dd9 2023-08-04 jrmu          [else (first alod1) (rest alod1) accu])))
21 12687dd9 2023-08-04 jrmu     (to10-accu alod0 ...)))