From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,9a586954b11ae008
X-Google-Attributes: gid103376,public
From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Overflows (lisp fixnum-bignum conversion)
Date: 1997/04/06
Message-ID: <E874Gq.91M@world.std.com>#1/1
X-Deja-AN: 231023167
References: <1997Apr2.202514.1843@nosc.mil> <E82sM5.Gwv@world.std.com>
 <Pine.SUN.3.96.970405054237.22894A-100000@eskimo.com>
Organization: The World Public Access UNIX, Brookline, MA
Newsgroups: comp.lang.ada
Date: 1997-04-06T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <Pine.SUN.3.96.970405054237.22894A-100000@eskimo.com>,
Clayton Weaver  <cgweav@eskimo.com> wrote:
>Std lisp limits array indexes to fixnums. Lisp can transparently cast the
>overflowing representation from fixnum to bignum, but it will still error
>if it tries to allocate an array ("vector") with an index size beyond the
>fixnum bound, unless you have a custom handler for that case that either
>changes the array to some other storage type or virtualizes the data
>structure into an array of arrays, and sets a flag that whatever function
>accesses that array can read to change its lookup method.

I won't complain if I can't allocate an array bigger than 2**32 bytes on
a machine that has a 32-bit address space.  That's a lot different from
telling me I can't allocate a 1000-bit integer on such a machine.

- Bob