commander-s/scheme/tty-debug.scm

(define debug-mode #f)

(define *tty-port* #f)

(define (init-tty-debug-output!)
  (and debug-mode
       (call-with-values 
	   open-pty
	 (lambda (input-port name)
	   (set! *tty-port* (dup->outport input-port))
	   (close input-port)
	  (set-port-buffering *tty-port* bufpol/block 8192)
	  name))))

(define debug-message
  (lambda args
    (if (and debug-mode *tty-port*)
	(with-current-output-port*
	 *tty-port*
	 (lambda ()
	   (for-each write args)
	   (newline)
	   (flush-tty/output *tty-port*))))))