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From: bimbart@kulcs.cs.kuleuven.ac.be (Bart Demoen)
Newsgroups: comp.lang.prolog
Subject: immediate update
Message-ID: <1386@n_kulcscs.kuleuven.ac.be>
Date: 26 Nov 90 21:45:46 GMT
Sender: news@cs.kuleuven.ac.be
Organization: Dept. of Computer Science (K.U.Leuven)
Lines: 35
Originator: bimbart@kulcs.cs.kuleuven.ac.be

hello,

sorry if the folowing questions seem non-relevant

given a Prolog implementation with the immediate update view on database changes,
what would you expect in the following situations:
(I insist on the word 'expect': even if you have an implementation of the immediate
update view, I am still most of all interested in your expectations)

a/1 is dynamic and there is one clause for a/1:

a(1) .

question 1
what is the output of the query

?- a(X) , write(X) , retract(a(1)) , asserta(a(2)) , fail .

question 2
what is the output of the query

?- a(X) , write(X) , retract(a(1)) , assertz(a(2)) , fail .

in case you overlooked it: the difference between the queries is in assertA/assertZ

----------

in which Prolog system has the immediate update view on database changes been
implemented ? can you test for me the above queries ?

you can send answers to me directly, I can summarize to the net

thanks

Bart Demoen