Frequently Asked Questions - comp.lang.prolog

Last-modified: 2008-02-15
Last-changes: Add Planet Prolog

Markus Triska (Mar. 2 2007 - ... )

Remko Troncon (Jan. 6 2002 - Mar. 2 2007)

Dirk-Jan Faber (Feb. 1 1999 - Jan. 6 2002)

Jamie Andrews (Aug 26 1992 - Oct. 16 1997)
__________________________________________________________________

General Information: This article contains the answers to some
Frequently Asked Questions (FAQ) often seen in
news://comp.lang.prolog/. It is posted (twice a month, currently on
the 2nd and 16th) to help reduce volume in this newsgroup and to
provide hard-to-find information of general interest.

The World Wide Web URL for this FAQ is:
http://www.logic.at/prolog/faq/

Questions about the FAQ and updates ought to be submitted to
.

1. What is the Association for Logic Programming?
2. Where can I get a free Prolog for system X (PC, Mac, Unix or other)?

Hello,

is there something like a canonical alternative to assert and retract?
In other words, are there algorithms for translating any Prolog
program that uses assert and retract into an equivalent program that
does without these predicates? And, if so, will the "compiled" (i.e.
the static) programs be, in general, equally or more or less
efficient? Do you know good articles about this issue?

Apart from aesthetical aspects, an obvious advantage of avoiding
assert and retract would be that one's programs are compatible with
more compilers. Thus, one could have Mercury or Yield Prolog compile
one's code.

The Mercury documentation is quite abstract about how to avoid assert
and retract: "The use of assert and retract should be replaced with a
collection data structure threaded through the relevant part of the
program."

Simon

On 2008-07-14, Michael Igler wrote:

This should run on any Prolog system:

writes(:-(A)) :- !,write((:-)),writes(A).

--- Jan

I need to translate the following code, that prints out the SLD tree,
from SWI-Prolog to Sictsus. It is part of the graphviz.pl file that can
be found at :

http://www.cs.bris.ac.uk/Teaching/Resources/COMS30106/graphviz/

The problem are these two lines when I try to load it in Sicstus 4.0.4:

writes(:-A) :- !,write(':-'),writes(A).
writes(?-A) :- !,write('?-'),writes(A).

Sicstus is telling me:

Hi,

I'm trying to update some old prolog (18 years or more old!). I've
come across a predicate con/3, but can't find any documentation on
it. Can anyone help with a definition?

Thanks

Simon

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Please send your nominations to Jimmy Lee cse.cuhk.edu.hk> to
arrive by midnight (California time) on August 10th, 2008.

Anyone already done a prolog program which identify the word when i
insert the beginning of the word:
?- Example: identify( 'bec',L).
?- L='because'

Please send me.

Thanks,

Diego Passos.

Michael Igler wrote:

Here you can find a metainterpreter that shows the SLDNF tree in LaTeX:

http://www.ing.unife.it/docenti/MarcoGavanelli/sldnfDraw/

Cheers,
Marco

Michael Igler wrote: