The IO [full module]

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(module io mzscheme 
  
  (provide 
   read-all ;; String -> [Listof String]
   ;; read a file as a list of strings 
   
   print-all ;; OutputPort [Listof String] -> Void
   ;; print a list of lines to output port 
   
   directory-exists? ;; String -> Boolean 
   ;; does the string represent a legal path to a directory/folder?
   
   file-exists? ;; String -> Boolean
   ;; does the string represent a legal path to a file? 
   
   )
  
  (require (lib "etc.ss") (lib "list.ss") (lib "file.ss"))
  
  (define (read-all file)
    (local (;; InputPort -> [Listof String]
            (define (read-all)
              (local ((define next (read-line)))
                (cond [(eof-object? next) empty]
                      [else (cons next (read-all))]))))
      (with-input-from-file file read-all)))
  
  (define (print-all op line*)
    (for-each (lambda (line) (fprintf op "~a\r\n" line)) line*))
  )

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