Racket is a scheme, but this infix notation is unique to racket, i.e. it's not in the scheme specification. In fact, there are other proposals for infix notatio

Racket is a scheme, but this infix notation is unique to racket, i.e. it's not in the scheme specification. In fact, there are other proposals for infix notation for scheme, such as http://srfi.schemers.org/srfi-105/srfi-105.html http://srfi.schemers.org/srfi-105/srfi-105.html