(define $main
  (lambda [$args]
    (match args (list string)
      {[<cons $file $nums> (cut file (map read nums))]})))

(define $cut
  (lambda [$file $nums]
    (do {[$port (open-input-file file)]
         (each-line-from-port port (lambda [$line] (let {[$fs (S.split "," line)]}
                                                     (print (S.intercalate "," (map (nth $ fs) nums))))))
         (close-input-port port)})))