arrow-gui.ss
The teachpack arrow-gui.ss
implements three functions:
Example:
> (define (make-model dir)
(lambda (b e)
(begin
(view dir)
(printf "~a ~n" (control)))))
> (connect
(make-model "left")
(make-model "right")
(make-model "up")
(make-model "down"))
Now click on the four arrows. The message field will contain the current
direction, the print-out the prior contents of the message field.