process-filter.ros

#!/bin/sh
#|-*- mode:lisp -*-|#
#|
exec ros -Q -- $0 "$@"
|#
(defvar *filters* '(/line))
(defvar *results* '())

(defun /line (output error)
  (values
   (lambda (input)
     (loop :for line := (read-line input nil nil)
        :while line
        :do (funcall output line)))
   error))

(defun to-stream (stream)
  (lambda (x)
    (typecase x
      (string (format stream "~A~%" x))
      ((simple-array (unsigned-byte 8) (*))
       (write-sequence x stream))
      (t (format stream "~S~%" x)))))

(defun main (&rest argv)
  (declare (ignorable argv))
  (loop
     :with output := (let ((output (to-stream *standard-output*)))
                       (lambda (input) (funcall output input)))
     :with error := (let ((output (to-stream *error-output*)))
                      (lambda (input) (funcall output input)))
     :for f :in *filters*
     :do (multiple-value-setq (output error)
           (funcall f output error))
     :finally (funcall output *standard-input*))
  (mapc #'funcall *results*))