customhash.rkt

#lang racket

(require racket/unsafe/ops)


(struct Cons (a d) #:transparent
  #:methods gen:equal+hash
  [(define (equal-proc c1 c2 =?)
     (and (=? (unsafe-struct-ref c1 0)
              (unsafe-struct-ref c2 0))
          (=? (unsafe-struct-ref c1 1)
              (unsafe-struct-ref c2 1))))
   (define (hash-proc c rec)
     (unsafe-fxior (rec (unsafe-struct-ref c 0))
                   (rec (unsafe-struct-ref c 1))))
   (define (hash2-proc c rec)
     (unsafe-fxior (rec (unsafe-struct-ref c 0))
                   (rec (unsafe-struct-ref c 1))))])

(define c1 (Cons 'a 'b))
(define c2 (Cons 'a 'd))
(define c3 (Cons 'b 'b))


(struct Pair (a d) #:transparent)

(define p1 (Pair 'a 'b))
(define p2 (Pair 'a 'd))
(define p3 (Pair 'b 'b))

(define (equal-test str v1 v2 v3)
  (displayln str)
  (time (for ([_ (in-range 1000000)])
          (define ans1 (equal? v1 v1))
          (define ans2 (equal? v1 v2))
          (define ans3 (equal? v1 v3))
          (void))))

(equal-test "Cons equal?" c1 c2 c3)
(equal-test "Pair equal?" p1 p2 p3)

#|
Cons equal?
cpu time: 473 real time: 477 gc time: 27
Pair equal?
cpu time: 216 real time: 218 gc time: 0
|#


(define (hash-test str v1)
  (displayln str)
  (time (for ([_ (in-range 1000000)])
          (define ans1 (equal-hash-code v1))
          (define ans2 (equal-secondary-hash-code v1))
          (void))))

(hash-test "Cons hash" c1)
(hash-test "Pair hash" p1)


#|
Cons hash
cpu time: 330 real time: 333 gc time: 4
Pair hash
cpu time: 153 real time: 155 gc time: 0
|#