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From: prj@po.cwru.edu (Paul Jarc)
Subject: Re: Resizing hash tables in Guile
Date: Thu, 13 Feb 2003 15:02:38 -0500	[thread overview]
Message-ID: <m365rodk3v.fsf@multivac.cwru.edu> (raw)
In-Reply-To: <kiwu1f8jan1.fsf@blinky.bloomberg.com> (HJSTEIN@bloomberg.net's message of "13 Feb 2003 13:30:58 -0500")

HJSTEIN@bloomberg.net (Harvey J. Stein) wrote:
> Joris van der Hoeven <TeXmacs@math.u-psud.fr> writes:
>> inserting requires looking up too.
>
> Yes, if you want to return an error for inserting 2 items with the
> same key.

Or if you want to replace existing entries, as Guile's current hash
tables do.

>> But you need a compairison operation for that,
>> which may be even less natural than a hash function.
>
> Yes.  For hash tables you just need a key equality test.  For trees
> you need to be able to order the keys.

It's easy enough to support this: (< (hash key1 0) (hash key2 0))
But this is probably only useful in the general case.  It should be
possible to substitute a less expensive ordering function when one is
available.


paul


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  reply	other threads:[~2003-02-13 20:02 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <Pine.GSO.3.96.1030208160743.22945E-100000@anh>
     [not found] ` <87lm0o7951.fsf@alice.rotty.yi.org>
     [not found]   ` <rmiu1fcnrhj.fsf@fnord.ir.bbn.com>
     [not found]     ` <1044889242.1033.310.camel@localhost>
     [not found]       ` <xy77kc8krhr.fsf@nada.kth.se>
     [not found]         ` <xy74r7ckqmy.fsf@nada.kth.se>
2003-02-11 13:59           ` Resizing hash tables in Guile Mikael Djurfeldt
2003-02-11 17:34             ` Roland Orre
     [not found]               ` <ljy94lhgkb.fsf@burns.dt.e-technik.uni-dortmund.de>
2003-02-12 17:47                 ` Mikael Djurfeldt
2003-02-12 20:44                   ` Rob Browning
2003-02-12 16:10             ` Marius Vollmer
2003-02-12 17:53               ` Mikael Djurfeldt
2003-02-12 20:17                 ` Roland Orre
2003-02-13  9:35                   ` Mikael Djurfeldt
2003-02-13 13:55                     ` Harvey J. Stein
2003-02-13 14:24                       ` Joris van der Hoeven
2003-02-13 18:30                         ` Harvey J. Stein
2003-02-13 20:02                           ` Paul Jarc [this message]
2003-02-13  9:52                   ` Joris van der Hoeven
2003-02-12 20:55             ` Rob Browning
2003-02-13 10:43               ` Mikael Djurfeldt

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