1-8-3.rkt~

;; 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 1-8-3) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f () #f)))
; A List-of-names is one of: 
; – '()
; – (cons String List-of-names)
; interpretation a list of invitees, by last name




; A List-of-names is one of: 
; – '()
; – (cons Bool List-of-names)
; interpretation a list of invitees, by last name


; List-of-names -> Boolean
; determines whether "Flatt" is on a-list-of-names
(define (contains-flatt? a-list-of-names)
  (cond [(empty? a-list-of-names) #false]
        [(string=? (first a-list-of-names) "Flatt") #true]
        [else (contains-flatt? (rest a-list-of-names))]))
        

(check-expect (contains-flatt? '()) #false)
(check-expect (contains-flatt? (cons "Flatt" '())) #true)