Getting started with Prolog
© 2004-2013 Jean-Marc Vanel - e-mail: Send your comments - My home page

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Your first Prolog session

There are numerous tutorials on Prolog on the Web, but they forget to tell indispensable howtos .

To start a Prolog interpreter on Linux (or cygwin ) enter;

swipl           # for SWI-Prolog 
yap             # for YaP
gprolog         # for GNU Prolog

To enter rules from the command line, type this :

[user].

This puts you in a mode where you can enter facts and rules. Otherwise you get this kind of message:

<>?- idiot(me).

ERROR: (user://2:121):

        Undefined procedure: idiot/1

You can then enter facts, e.g. :

father(me,sarah).

Or rules, e.g. :

father(X,Y) :- male(X), parent(X,Y).

After having entered the knowledge, type CONTROL-D to come back to the mode where you can enter goals (questions). Then you can ask:

| ?- father(me,X).
X = sarah
yes

To quit:

halt.

Using files

Create a file father.pl containing what we entered in the "enter facts and rules" mode. Then you can load this file under Prolog by typing this:

[father].

You can then enter goals like before.

Using the SWI Prolog IDE

This will start a Prolog editor on a new file, with realtime syntax highlight and check :

edit(file('father.pl')).

Paste this in the Prolog editor :

% facts:
male('Nat King Cole').
parent( 'Nat King Cole', 'Nathalie Cole').
father(me,sarah).
% rules :
father(X,Y) :- male(X), parent(X,Y).

Then select and click Compile / Compile buffer .

You can then ask queries in the command-line window :

?- father(X, Y).
X = me,
Y = sarah

Then type a semicolon (;) to get the next solution:

X = 'Nat King Cole',
Y = 'Nathalie Cole'.

?-

A dot (.) is printed, as it is the last solution, and the prompt re-appears.

Prolog links

Documentation / tutorials

The official prolog FAQ is a wonderful resource: http://www.logic.at/prolog/faq< wbr>/faq.html

Graph structures and paths, part of a real nice Prolog course entirely by examples, by J.R. Fisher, mentioned in:

Tutoral list in the Prolog FAQ

Learning Prolog (Univ. Saarland)

Electronic books by : Nilsson, Artificial Intelligence through Prolog by Neil C. Rowe ( can be found here and there on the Web)

Problems, code examples

P-99: Ninety-Nine Prolog Problems, by Werner Hett

The First 10 Prolog Programming Contests

code from book "the Art of Prolog"

Solutions to some exercises in "The Art of Prolog"

Prolog implementations

SWI-Prolog

Yap

XSB 

TuProlog , JLog ( in Java )

The GNU Prolog web site

SICStus Prolog User's Manual - Table of Contents

Links to review

The links below need updating/review :

The Prolog Dictionary

Introduction to Prolog

Prolog Tutorials

Prolog Tutorial -- Contents

Prolog Tutorial

Prolog for Software Engineering

Free Online Prolog Tutorials (thefreecountry.com)

The Prolog language

Relational database programming

Introduction

http://www.cetus-links.org/oo_prolog.html

Blogs

http://www.cs.kuleuven.be/~toms/PlanetProlog/ - Tom Schrivers, one author of CHR
http://www.cs.kuleuven.be/~bmd/ - home page of Bart Demoen

Software

GNU Prolog GNU Prolog is a free implementation (under GPL) of the logic programming language PROLOG. It can compile to native machine code which is extremely fast in execution. Another feature is the included constraint solver.

JPL A set of Java classes and C functions providing a bridge between Java and Prolog
jsprolog An implementation of a Prolog inferencing engine in browser-friendly javascript.

????
PESS - Prolog Expert System Shell The Prolog Expert System Shell (PESS) is a software that generates ES using basically two components: Knowledge Base, used by the ES to guide its decisions making, and Inference Machine, cable of collection the rules and generating new facts.

Interfacing data sources with Prolog

Relational data sources

XML data sources

Interfacing GUI or Web applications with Prolog