On Wed, Feb 19, 2020 at 10:31 AM Lassi Kortela <xxxxxx@lassi.io> wrote:
 
If the custom methods are stored in an alist, how do users of the port
call them? Is it like (call-port-method port 'method args...), or is
there a fixed set of methods per each version of MIT Scheme?

This returns the position procedure:

  (port/operation (current-output-port) 'position)