(define-struct Person (name year kids))

(define Bart (make-Person 'Bart 1979 empty))
(define Lisa (make-Person 'Lisa 1981 empty))
(define Maggie (make-Person 'Maggie 1988 empty))
(define Homer (make-Person 'Homer 1955 (list Bart Lisa Maggie)))
(define Marge (make-Person 'Marge 1956 (list Bart Lisa Maggie)))
(define Selma (make-Person 'Selma 1950 empty))
(define Patty (make-Person 'Patty 1950 empty))
(define Jackie (make-Person 'Jackie 1926 (list Selma Patty Marge)))
(define Herbert (make-Person 'Herbert 1950 empty))
(define Mona (make-Person 'Mona 1929 (list Herbert Homer)))
(define Abe (make-Person 'Abe 1920 (list Herbert Homer)))

Abe


;; Person->string: Person -> string (duh!)
;; Return the string representation of a-p, as described in lab06.html
;;
(define (Person->string a-p)
  (Person->string-help a-p ""))

; bullet: string
; What to put in front of each name
;
(define bullet "-")

; generation-indent: string
; How to indent each succeeding generation.
;
;(define generation-indent "  |")
(define generation-indent
  ; A more complicated version: a long bullet requires more generation-indent.
  (string-append (make-string (string-length bullet) #\space)
                 " |"))
  

;; Person->string-help: Person, string -> string
;; Return the string representation of "a-p", except that
;; each line is prepended with "prefix".
;;
(define (Person->string-help a-p prefix)
  (string-append prefix
                 bullet 
                 (symbol->string (Person-name a-p))
                 " (b. "
                 (number->string (Person-year a-p))
                 ")"
                 newline
                 (Persons->string (Person-kids a-p)
                                  (string-append prefix generation-indent))))

;; Persons->string: list-of-person string --> string
;; Return the string representation of everybody in "people",
;; all concatenated into a single string,
;; with each line prepended by "prefix".
;;
(define (Persons->string  people prefix)
  (cond [(empty? people) ""]
        [(cons?  people)
         (string-append (Person->string-help (first people) prefix)
                        (Persons->string (rest people) prefix))]))

(display-string (Persons->string empty "tra"))
(display-string (Persons->string (list Bart) "lala"))
(display-string (Person->string  Bart))
(display-string (Persons->string (list Bart Lisa Maggie) "tra"))
(display-string (Person->string  Marge))
(display-string (Person->string  Jackie))