Source code in the racket programming language

(define (foo x)
  (define (bar y) (+ x y))
  (bar 2))
(foo 1) ; => 3
(bar 1) ; => error


(define (foo x)
  (define (bar y) (+ x y))
  bar)
(foo 1)     ; => #<procedure:bar>
((foo 1) 2) ; => 3