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Logtalk 3.x development version
Logtalk Prolog HTML Common Lisp Shell Inno Setup Other

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adapters Update the Lean Prolog adapter file wit support for using `index/1` d…
coding Fix Rogue syntax highlighter notes
contributions Fix some documentation typos
core Fix a bug where singleton variables in included file terms would resu…
docs Add missing entries to the `help` tool for the message printing and q…
examples Fix a couple of documentation hooks
integration JIProlog 4.0.18 or a later version is now required as this version in…
library Add `nd_assignvars.lgt` file missing in the previous stable release
man/man1 Update the header of the `jiplgt` script man page
manuals Document limitation on using some `logtalk_load_context/2` keys when …
paths Add example of supporting application localization in multiple languages
scratch Update copyright notice for 2015
scripts Update version to 3.00.7 in preparation for the next release
tests Add unit test for the `numbervars/3` de facto standard predicate for …
tools Add missing entries to the `help` tool for the message printing and q…
.gitignore Add missing `.gitignore` entry for the temporary file directory usual… Update copyright notice for 2015
BIBLIOGRAPHY.bib Update version to 3.00.7 in preparation for the next release Update customization notes Change all references to "compiler option" to "compiler flag" for con…
LICENSE.txt Minor clarification of the licensing terms Change all references to "compiler option" to "compiler flag" for con… Improve section on contributions on the `` file Fix a bug where singleton variables in included file terms would resu… Update copyright notice for 2015
VERSION.txt Update version to 3.00.7 in preparation for the next release
loader-sample.lgt Minor documentation fixes
settings-sample.lgt Minor documentation updates
tester-sample.lgt Update copyright notice for 2015

This file is part of Logtalk
Copyright (c) 1998-2015 Paulo Moura

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see

Additional licensing terms apply per Section 7 of the GNU General Public License 3. Consult the LICENSE.txt file for details.


  1. About
  2. Logtalk web site
  3. Registration
  4. Support
  5. Installation
  6. Customization
  7. Running
  8. Documentation
  9. Upgrading
  10. Citations
  11. Contributions
  12. Legal


Logtalk is an object-oriented logic programming language that extends and leverages the Prolog language with a feature set suitable for programming in the large. As a multi-paradigm language, it includes support for both prototypes and classes, protocols (interfaces), component-based programming through category-based composition, event-driven programming, coinduction, and high-level multi-threading programming. Logtalk uses standard Prolog syntax with the addition of some operators and directives and can be used with any Prolog implementation compliant with official and de facto standards as the back-end compiler.


The latest release of the Logtalk is always available at the URL:

At this address you can also find additional documentation and information about Logtalk.


To register as a Logtalk user either use the registration form found at the Logtalk web site:

or send an email message to:

with the following information:

email address, first and last name, organization, organization type (education, commercial, government, ...), Prolog compilers you use (optional), platforms (mac, pc, unix,...) (optional), projects where you intend to use Logtalk (optional)


For support options, please consult the web page:


Logtalk can be installed either from sources by running a few shell scripts or by using one of the provided installers, depending on your operating system. For manual installation, see the file for detailed instructions.

See the user manual for a description of the source files organization and for using instructions (to read the user manual open the index file in a web browser). Most files are formatted using tabs (the recommended setting is a tab width equivalent to 4 spaces).


The file provides detailed instructions for customizing the Logtalk installation and working environment.


The file provides quick instructions for those of you in a hurry to run Logtalk, provided that your favorite Prolog compiler is supported and installed.


The reference and user manuals and the tutorial are provided in XHTML and PDF formats and can be found in the manuals directory.

The file contains descriptions of all Logtalk updates since the first public version. Read it carefully if you have been using a previous Logtalk version.

The documentation for the core, library, tools, and contributions entities is provided in XHTML format and can be found in the docs directory.

Most directories include documenting files, which can be viewed as plain text in any text editor but also nicely rendered as Markdown files (for e.g. easy conversion to HTML).

On POSIX systems, there's also a man page for each shell script. A list of all the scripts can be generated using the apropos logtalk command.


If you are upgrading from a previous Logtalk version, please check the file for instructions on how to upgrade your programs or your custom adapter files to run under this new version.


If you find Logtalk useful, please include a citation on your publications. Consult the BIBLIOGRAPHY.bib file for bibliographic references in BibTeX format (the Logtalk technical report published on 2000 and the 2003 PhD thesis on Logtalk are good choices).


Contributions, constructive criticism, patches, bug reports, and suggestions are always welcome. Major code contributions to core files, such as the compiler, runtime, adapter files, library files, or developer tools can only be accepted with a transfer of copyright or if the submitted code is explicitly declared as public domain code. This simplifies the selling of commercial licenses, which provide a revenue source for the sustained development of Logtalk. Contributions that retain the copyright of their authors may also be distributed with Logtalk with the understanding that the terms of their commercial use depends solely on the authors chosen licensing terms and may require a separate, independent, agreement between users and authors.


Logtalk is copyrighted by Paulo Moura. The Logtalk use and distribution license can be found in the LICENSE.txt file. Logtalk is available under the GNU General Public License 3 with a linking exception. The copyright notice and license applies to all files in this release unless otherwise explicitly stated.

Some files that are part of the Logtalk distribution are distributed using a different license and/or are copyrighted by a Logtalk contributor.

Some of the included examples are adaptations to Logtalk of Prolog examples found elsewhere (e.g. in manuals, tutorials, books, and public mailing list discussions). The copyright in the examples original code should be assumed to belong to the original authors.

Logtalk is a registered trademark of Paulo Moura.

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