Re: Scheme style auto-resizing hashtable (fwd)

[Kohtala Marko <Marko.Kohtala@ntc.nokia.com>]

I lost the beginning of your discussion, but could your iterators be a
cons cell where the cdr value is delayed?

This would be neater, if cdr, map and for-each implicitly forced the
cdr, but for the below example I define ++ to replace cdr.

Like this:

(define (hash->list v)
  (let ((l (vector-length v)))
    (define (h2l v nth handles)
      (cond
        ((= nth l) ())
        ((pair? handles) (cons (car handles)
			       (delay (h2l v nth (cdr handles)))))
	((= (1+ nth) l) ())
	(else
	 (h2l v (1+ nth) (vector-ref v (1+ nth))))))
      (h2l v -1 ())))
(define (++ c)
	(force (cdr c)))

(define t (make-hash-table 13))
(hashq-set! t 'a 'b)
(hash->list t) => ((a . b) . #<promise #<procedure ()>>)
(++ (hash->list t)) => ()

-- 
Marko Kohtala - Marko.Kohtala@ntc.nokia.com, Marko.Kohtala@hut.fi