(use-modules (rnrs io ports))
(use-modules (ice-9 threads))


(define (on-file-change fname thunk)
  (let* ((input+output (pipe))
	 (pid (spawn "inotifywait" `("inotifywait" "-m" ,fname)
                     #:output (cdr input+output))))
    (close-port (cdr input+output))
    (let loop ((line "dummy CLOSE_WRITE"))
      (unless (eof-object? line)
	(format #t "read ~s~%" line)
	(if (string-contains line "CLOSE_WRITE")
	    (thunk))
	(loop (get-line (car input+output)))))
    (close-port (car input+output))
    (waitpid pid)))

(call-with-new-thread (lambda ()  (on-file-change "inotify-test.scm" (lambda () (format #t "file changed~%")))))

(format #t "waiting 30s for file change~%")
(do ((i 0 (+ i 1)))  ((> i 30) (format #t "done loop~%"))
  (sleep 1)
  (format #t "tick~%"))
(format #t "done waiting~%")