modifying the scheme reader in DrScheme

[Michael Vanier <mvanier@bbb.caltech.edu>]

I have this idea for a minor syntactic extension to the scheme reader that
would allow me to use end tags in s-expressions e.g.

(define (bar x y)
  (if (< x y)
      (* 2 x)
	  (* 2 y)
  .if) ; end tag for if
.define) ; end tag for define

The reader checks that the end tags match, and then discards them.

Is there any way to do something like this in DrScheme?  The support for
scheme dialects leads me to think that this should be possible, but I
suspect it's wizard-level programming.

Mike