(define-struct fileinfo (name format size path))
;; A FileInfo is a (make-fileinfo Str Sym Num Str)
;; requires:
;;          name is a non-empty string
;;             that contains only alphanumeric characters
;;          format is one of 'doc, 'txt, 'rtf, 'zip,
;;             'raw, 'jpg, 'wav, 'mp3
;;          size > 0, and represents the size of the file in kilobytes
;;          path is a non-empty string that
;;             starts with a / character and ends with an alphanumeric character
;;             contains only / and alphanumeric characters
;;             with at least one alphanumeric character
;;             that appears between any two / characters
;;             (representing the name of a folder)

;; A Directory is a (listof FileInfo)
;; requires:
;;    the elements of the list represent information about
;;        files contained in the Directory
;;    all elements of the list have the same path
;;    each element of the list is uniquely identified by
;;        its name and format (i.e. its full name)

(define (dir-size direct)
  (cond
    [(empty? direct) 0]
    [(+ (fileinfo-name])