;; direct mechanism
(call-with-input-file "/etc/passwd"
  (lambda (port)
    (do ((expr (read port) (read port)))
        ((eof-object? expr))
        (print expr))))

;; convenience functions
(define (call-with-read-lines file proc)
  (call-with-input-file file
    (lambda (port)
      (do ((expr (read-line port) (read-line port)))
          ((eof-object? expr))
        (proc expr)))))

(define (call-with-read file proc)
  (call-with-input-file file
    (lambda (port)
      (do ((expr (read port) (read port)))
          ((eof-object? expr))
        (proc expr)))))

(define (read-lines file)
  "alternative: file->string-list"
  (let1 result ()
    (call-with-input-file file
      (lambda (port)
        ;; TODO simplu call port->sexp-list or port->string-list
        (do ((expr (read-line port) (read-line port)))
            ((eof-object? expr))
          (set! result (cons expr result)))))
    (reverse result)))

(call-with-read-lines "/etc/passwd" print)