どうかく？の問題

http://ja.doukaku.org/comment/511/

楽勝。

(require :iterate)
(in-package :iter)
(defun remove-comments (in out)
  (iter (for line in-stream in using #'read-line)
        (unless (char= (aref line 0) #\#)
          (write-line line out))))

(defun test ()
  (with-open-file (in "10.input" :direction :input)
    (with-open-file (out "10.output" :direction :output :if-exists :supersede)
      (remove-comments in out))))

(test)