実行時間の計測レポート

(defmacro report-to-file (filename repeat &body form)
  (let ((report-out (gensym))
        (idx (gensym)))
    `(with-open-file (,report-out ,filename :direction :output)
       (let ((*trace-output* ,report-out))
         (loop for ,idx from 1 upto ,repeat
               do  
               (format ,report-out "==== PROF ~A ====~%" ,idx)
               (time ,@form))))))