[plt-scheme] Hash Table implementation

Things also behave as expected with 'equal if the keys are strings
instead of fractions.  So the bug is related to the equal? checking
for numbers, specifically.

On 8/3/07, Keith Frost <keith.l.frost at gmail.com> wrote:
> Weird... I get this too.  By the way, if you drop the 'equal symbol,
> and use fixnums instead of fractions, the strange behavior goes away.
> So it's a bug that depends on the equality-checking...
>
> Keith F.
>
> On 8/3/07, David Einstein <deinst at gmail.com> wrote:
> > Inspired by Jens and Grant, I decided to try my hand at some of the Project
> > Euler problems using PLT scheme, to see what it was capable of.  It has
> > proven itself capable on the few problems that I have completed so far, but
> > I just ran into what appears to be a bug of sorts.  It appears that the
> > hash-table implementation does not expand as more keys are added, and so if
> > the table reaches a certain size things slow down dramatically.  For example
> >
> > (require (lib "42.ss" "srfi"))
> >
> > (define (randfrac n)
> >   (/ (+ 1 (random n)) (+ 1 (random n))))
> >
> > (define ht (make-hash-table 'equal))
> > (time (do-ec (: a 1 1000) (hash-table-put! ht (randfrac 1000) #t)))
> > (time (do-ec (: a 1 10000) (hash-table-put! ht (randfrac 1000) #t)))
> > (time (do-ec (: a 1 100000) (hash-table-put! ht (randfrac 1000) #t)))
> >
> > results in
> >
> > Welcome to DrScheme, version 370 [3m].
> > Language: Graphical (MrEd, includes MzScheme); memory limit: 1024 megabytes.
> > cpu time: 0 real time: 0 gc time: 0
> > cpu time: 125 real time: 125 gc time: 0
> > cpu time: 13047 real time: 13047 gc time: 0
> > >
> >
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> >
> >
>