s c h e m e w i k i . o r g

(define (for-each-line-in-file filename proc . mode)
  (with-input-from-file
   filename
   (lambda () (apply for-each-line proc (current-input-port) mode))))

(define (for-each-line proc . port+mode)
  (let while ()
    (let ((line (apply read-line port+mode)))
      (unless (eof-object? line)
        (proc line)
        (while)))))