;; The first three lines of this file were inserted by DrRacket. They record metadata ;; about the language level of this file in a form that our tools can easily process. #reader(lib "htdp-beginner-reader.ss" "lang")((modname 20.4.1) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ()))) ; Worked exercise 20.4.1 ; right-of-100? : posn -> boolean (check-expect (right-of-100? (make-posn 75 123)) false) (check-expect (right-of-100? (make-posn 102 123)) true) (check-expect (right-of-100? (make-posn 100 123)) false) (define (right-of-100? the-posn) ; the-posn a posn ; (posn-x the-posn) a number (the x coordinate) ; (posn-y the-posn) a number (the y coordinate) ; 100 a fixed number we know we'll need (> (posn-x the-posn) 100) )