;; A ListOfString (LoS) is either
;; -- empty
;; -- (cons String LoS)

#|
;; f: LOS -> ??
(define (f l)
  (cond
    [(empty? l) ... ]
    [(cons?  l) ... (first l) ... (f (rest l) ... ) ]))
|#


;; list->string: LoS -> String
;; appends all the Strings in los
(define (string-list los)
  (cond
    [(empty? los) ""]
    [(cons?  los) (string-append (first los) 
                                 " "
                                 (string-list (rest los)))]))

;; Examples/Test
(string=? (string-list empty) "")
(string=? (string-list (cons "1" empty)) "1 ")
(string=? (string-list (cons "1" (cons "2" empty))) "1 2 ")