Racket does not use S-Expressions internally, it uses syntax objects which are not really the same. Furthermore it makes no sense to even ascribe one surface syntax to Racket since it's more than one language really. Also if you ask the main developers of Racket if it's homoiconic they would probably tell you that it's irrelevant (and they would be right). In fact I have this in my IRC logs, "<samth> homoiconicity is a meaningless term that tells you nothing about macros"