define-new-binding.rkt

#lang racket/base

(require (for-syntax racket/base)
         syntax/parse/define)

(let ()
  (define-syntax-parse-rule (define-sum S)
    (define (S n)
      (if (= n 0) 0 (+ n (S (- n 1))))))

  (define-sum sigma)
  (sigma 5))

var-is-visible.rkt

#lang racket/base

(require (for-syntax racket/base)
         syntax/parse/define)

(let ()
  (define var-in-the-scope "this var is in the scope")
  (define-syntax-parse-rule (get-var)
    var-in-the-scope)

  (get-var))

(let ()
  (define-syntax-parse-rule (get-this-too)
    also-in-the-scope)
  (define also-in-the-scope "this var is also in the scope")

  (get-this-too))