I'm following Prof. Harvey's cs61a and among the files made available, there is one that implements Object Oriented Paradigm (here). When loading it to Dr. Racket and adding the simply-scheme language (#lang simply-scheme), I get the following error:
define-macro: unbound identifier in: define-macro
I'm not sure how to circumvent this problem, look for different sources but was not able to find a direction.
Thank you for the help!
The source file linked begins:
;;; obj.scm version 4.0 5/18/2000
;;; -- implementation of the object-oriented syntax
;; By Matt Wright, based on a handout from MIT
;; Revised for STk by Brian Gaeke - removed scm and procedure->macro
So it seems the source for is for STk and not Racket.
These days Racket no longer uses define-macro-style macros.
Best advice: Ask on https://racket.discourse.group/ and hope someone has implemented the OO-syntax.
It would be helpful, if you included a description of the OO-syntax (like the MIT handout).
Note that Harvey writes to install UCB (their version of STk): https://inst.eecs.berkeley.edu//~cs61a/sp11/
EDIT
https://github.com/zackads/sicp/blob/main/inst.eecs.berkeley.edu/~cs61as/fa11/lib/obj.rkt