Re: [Chicken-users] Memoizing a procedure

[F. Wittenberger]

Am Montag, den 29.11.2010, 10:34 -0300 schrieb Stephen Eilert:
So it is not only "memoization", but a caching system. I was going to
> write something similar, to cache webservice responses.
> 
That it is.

I've got several caches working with the attached code.

The API is kind of patterned after SRFI-69.

It tried however to hide that we're using hash tables, since that I
might want to experiment with.

If that fits approximately your needs I'd love to share the code.  --
and get your comments (API suggestions anyone?).

(It's not yet available as an egg, though.)

Here's an example which hopefully explains how to use it.

(define *resync-cache*
  (make-cache "*resync-cache*"
              eq?
              #f ;; state
              ;; miss:
              (lambda (cs k) (cons k #f))
              ;; hit
              #f ;; (lambda (c es) #t)
              ;; fulfil
              (lambda (c es results)
                (set-cdr! es (if (and (pair? results) (aggregate? (car 
results))) 
                                 #f
                                 (add-duration
                                  *system-time*
                                  (make-time
                                   'time-duration 0
                                   (or (respond-timeout-interval) 20)))))
                (values))
              ;; valid?
              (lambda (es)
                (or (not (cdr es))
                    (srfi19:time<=? *system-time* (cdr es))))
              ;; delete
              #f ;; (lambda (cs es) #f)
              ))

(cache-ref *resync-cache* oid
        (lambda () (%find-frame-sync! oid #f context)))

cache.scm
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