(define (read-file filename)
  (define (loop)
    (let ((line (read-line)))
      (if (eof-object? line)
          '()
          (cons line
                (loop)))))
  (with-input-from-file filename loop))

;this works:
(define (read-file2)
  (with-input-from-file "stuff.txt"
    (lambda ()
      (let loop ((line (read)))
        (unless (eof-object? line)
          (print line)
          (newline)
          (loop (read)))))))

;this works (it's a helper function):
(define (iterate finished? producer consumer)
    (let loop ((product (producer)))
      (unless (finished? product)
        (consumer product)
        (loop (producer)))))

;this works
(define (read-file3)
  (with-input-from-file "stuff.txt"
    (lambda ()
      (iterate eof-object? read 
               (lambda (line)
                 (print line)
                 (newline))))))
             
(define (read-file4)
  (with-input-from-file "stuff.txt"
    (lambda ()
      (let loop ( (line #f))
        (set! line (read))
        (unless (eof-object? line)
          (print line)
          (newline)
          (loop #t))))))