GNU PROLOG
                                ==========

INTRODUCTION
************

GNU Prolog is a native Prolog compiler with constraint solving over finite
domains (FD) developed by Daniel Diaz (http://cri-dist.univ-paris1.fr/diaz/)
Last information can be found at http://www.gnu.org/software/prolog
or better at http://www.gprolog.org.

A lot of work has been devoted to the ISO compatibility. GNU Prolog is very
close to the ISO standard.

Here are some features of GNU Prolog:

Prolog system:

   - conforms to the ISO standard for Prolog (integer/floating arithmetic,
     streams, dynamic code, exceptions).
   - clause indexing.
   - a lot of extensions: global variables, definite clause grammars (DCG),
     sockets interface, operating system interface,...
   - more than 300 Prolog built-in predicates.
   - Prolog debugger and a low-level WAM debugger.
   - line editing facility under the interactive interpreter with completion
     on atoms.
   - powerful bidirectional interface between Prolog and C.

Compiler:

   - native-code compiler producing stand alone executables.
   - simple command-line compiler accepting a wide variety of files:
     Prolog files, C files, WAM files,...
   - direct generation of assembly code 15 times faster than wamcc + gcc.
   - most of unused built-in predicates are not linked (to reduce the size
     of the executables).
   - compiled predicates (native-code) as fast as wamcc on average.
   - consulted predicates (byte-code) 5 times faster than wamcc.

Constraint solver:

   - FD variables well integrated into the Prolog environment (full
     compatibility with Prolog variables and
   - integers). No need for explicit FD declarations.
   - very efficient FD solver (comparable to commercial solvers).
   - high-level constraints can be described in terms of simple primitives.
   - a lot of predefined constraints: arithmetic constraints, boolean
     constraints, symbolic constraints, reified constraints,...
   - several predefined enumeration heuristics.
   - the user can define his own new constraints.
   - more than 50 FD built-in constraints/predicates.



PORTS
*****

GNU Prolog is currently ported to the following architectures:

   - ix86 / GNU/Linux
   - ix86 / Win32 using Cygwin (see file src/WINDOWS-OLD)
   - ix86 / Win32 using MinGW  (see file src/WINDOWS-OLD)
   - ix86 / Win32 using MSVC++ (see file src/WINDOWS-OLD)
   - ix86 / SCO
   - ix86 / Solaris
   - ix86 / FreeBSD
   - ix86 / OpenBSD
   - ix86 / NetBSD
   - ix86 / Darwin (Mac OS X)
   - x86_64 / GNU/Linux
   - x86_64 / Solaris
   - x86_64 / Win64 using MinGW64 (see file src/WINDOWS)
   - x86_64 / Win64 using MSVC++  (see file src/WINDOWS)
   - x86_64 / Darwin (Mac OS X)
   - PowerPC / GNU/Linux
   - PowerPC / Darwin (Mac OS X)
   - PowerPC / NetBSD
   - sparc / SunOS (4.1.3 or higher)
   - sparc / Solaris
   - sparc / NetBSD
   - sparc64 / Solaris
   - sparc64 / OpenBSD
   - alpha / GNU/Linux
   - alpha / OSF1
   - mips / irix
   - arm 32bits / GNU/Linux (armv6, armv7) 
   - arm 64bits (aarch64)/ GNU/Linux (armv8)
   - arm 64bits (aarch64) / Darwin (Mac OS X) (armv8)
   - RISC-V 64bits / GNU/Linux



INSTALLATION
************

Please refer to the INSTALL file (in the same directory)



USING GNU PROLOG
****************

Be sure that adequate environment variables are set (see INSTALL)

You can then invoke the top-level using:

	gprolog

and the compiler using:

	gplc FILE

The simplest way to compile a Prolog file 'prog.pl' is then:

	gplc prog.pl

which will produce the executable called prog (use gplc --help to have a
brief overview of available options).

Refer to the documentation for more information (see below).



WINDOWS
*******

In Microsoft Windows if you intend to use the gplc compiler as described in
the documentation you need to ascertain the following conditions are
met:

   - for the port compiled with Microsoft Visual C++ (aka MSVC++)
     (tested with Microsoft Visual Studio 2019 Community) you'll need
     MinGW as.exe (renamed as mingw-as.exe) installed and the cl.exe
     compiler (used mainly as linker by GNU Prolog) available in 
     your session path (alternatively link.exe is used).

   - for the ports compiled either with MinGW, the gcc toolchain
     must be installed and available in your session path.

Observing these needs you'll also will be able to do the mixed
language programming, as the examples included in the ExamplesC
directory. However you'll need to write your own Makefile as the one
provided is for gplc calling 'gcc' and the options passed by GNU
Prolog will not work (see file ExamplesC/README).



DOCUMENTATION
*************

The directory doc contains various versions of the manual. Refer to the
file doc/README for more information.

An in-line HTML version can be accessed from the GNU Prolog web page.



WEB
***

The GNU Prolog web site is: http://www.gnu.org/software/prolog/
or also (primary web site): http://www.gprolog.org/



MAILING LIST
************

To communicate with other GNU Prolog users and/or implementors send a mail to
users-prolog@gnu.org. To (un)subscribe to this mailing list send a mail to
users-prolog-request@gnu.org with (un)subscribe in the subject line.



BUGS
****

Please report bugs to bug-prolog@gnu.org. To (un)subscribe to this mailing
list send a mail to bug-prolog-request@gnu.org with (un)subscribe in the
subject line.



COPYING
*******

GNU Prolog is free software. Since version 1.4.0, GNU Prolog distributed
under a dual license: LGPL or GPL. So, you can redistribute it and/or modify
it under the terms of either:

  * the GNU Lesser General Public License (LGPL) as published by the Free
    Software Foundation; either version 3 of the License, or (at your option)
    any later version.

or 

  * the GNU General Public License (GPL) as published by the Free Software
    Foundation; either version 2 of the License, or (at your option) any
    later version.  

or both in parallel (as here).

GNU Prolog 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 copies of the GNU General Public License and the GNU
Lesser General Public License along with this program. If not, see
http://www.gnu.org/licenses/.

Remark: versions of GNU Prolog prior to 1.4.0 were entirely released under
the GNU General Public License (GPL).