Just a small question:  Are the accessors visible in the protocol <exp>?

Here is an example that would use this to copy a record.

(define-record-type point

   (protocol
     (lambda (new)
       (case-lambda
         ((x y)       (new x y))                     ; Create new
         ((old-point) (new (point-x old-point)       ; Copy existing
                           (point-y old-point)))))

   (fields (immutable x)
           (immutable y)))

Regards
Andre