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From: roland@sics.se (Roland Karlsson)
Newsgroups: comp.lang.prolog
Subject: Re: Arrays in Prolog
Message-ID: <1990Aug30.065319.2130@sics.se>
Date: 30 Aug 90 06:53:19 GMT
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In-Reply-To: vu0310@bingvaxu.cc.binghamton.edu's message of 29 Aug 90 15:14:56 GMT


> We have the possibility of doing things like communicating
> between alternatives in a disjunction, or implementing arrays
> (does Sicstus allow large arities for structs -- it's
> a bit hard to do (e.g. in "copyterm" -- part of the assert/clause
> mechanism) everywhere)? This comes in handy for implementing
> bagof/3, etc.

The only way the user can communicate between different Or-branches is
via the database (or a file or a UNIX* socket).  Bagof etc. is
implemented with an optimized version of database predicates.  A
system programmer can use a destructive setarg that never restores its
value at backtracking.

I am very very sad (%-<). SICStus only allows up to 256 arguments for struct.


--
Roland Karlsson
SICS, PO Box 1263, S-164 28 KISTA, SWEDEN	Internet: roland@sics.se
Tel: +46 8 752 15 40	Ttx: 812 61 54 SICS S	Fax: +46 8 751 72 30