set.rkt

; Purely functional implementation of Set data structure

(define set-init
  (lambda (x) #false))

(define (set-add set x)
  (lambda (y)
    (if (= x y)
        #true
        (set y))))

(define (set-union set1 set2)
  (lambda (y)
    (or (set1 y) (set2 y))))

(define (set-intersect set1 set2)
  (lambda (y)
    (and (set1 y) (set2 y))))