PySWIP INSTALL
==============

PySWIP requires SWI-Prolog as a shared library since it uses ctypes to access SWI-Prolog/C functions. The shared library is present in the Win32 installer, but missing by default from the builds made directly from the source.

Installing on Linux
-------------------

These instructions are tested on a Linux system, but should also work for POSIX systems. Also, you may want to install development packages for readline, libncurses, and libgmp.

You need to do the following to install a shared library enabled version of SWI-Prolog. We use version 6.0.2 of SWI-Prolog. Please make the necessary modifications for your environment.

1) Get the source from http://www.swi-prolog.org/download/stable:

	$ wget http://www.swi-prolog.org/download/stable/src/pl-6.0.2.tar.gz

2) Extract the archive and cd into it:
	
	$ tar xzvf pl-6.0.2.tar.gz
	$ cd pl-6.0.2.tar.gz

3) Configure the source with shared library enabled:

	$ ./configure --enable-shared
	
   *** If using a 64-bit system, you may have to compile with the -ggdb flag in order to get PySWIP to work with SWI-Prolog without segfaults (But not necessarily.  YMMV.):
   
	$ CFLAGS=-ggdb ./configure --enable-shared

4) Compile the source:

	$ make

5) Install the source:
	
	$ sudo make install
	
6) *** This is perhaps no longer relevant, as it appears clp is installed by default with SWI-Prolog
	clp library is useful for constraint handling problems, so let's install that too:

	$ cd cd packages/clpqr
	$ ./configure --enable-shared
	$ make && make install

7) If you are not using Python 2.5 or later, you should install ctypes, or get a new version of Python (apt-get is fine if you're using Ubuntu).

8) Unpack PySwIP package and install it with, ``python setup.py install``.

9) After you install it, you can test it with the following at your Python shell::

	>>> from pyswip import Prolog
	>>> prolog = Prolog()
	>>> prolog.assertz("father(michael,john)")
	
If you get an error, such as "libpl (shared) not found." or "FATAL ERROR: Resource not found" be sure you have installed SWI-Prolog as a shared library. Check your default library directory (usually ``/usr/lib``) for ``libswipl.so``.


Installing on Win32
-------------------

1) Get a recent version of SWI-Prolog for Win32 from: http://www.swi-prolog.org/dl-stable.html and install it.

2) You need to add SWI-Prolog's bin directory ``C:\Program Files\pl\bin`` to *path*, here are two tutorials for that:  http://www.computerhope.com/issues/ch000549.htm and http://vlaurie.com/computers2/Articles/environment.htm

3) Get a Windows installer version of PySWIP and install it.

4) After you install it, you can test it with the following at your Python console::

	>>> from pyswip import Prolog
	>>> prolog = Prolog()
	>>> prolog.assertz("father(michael,john)")


