PySWIP README
============
:Version:
0.2.2
:Author:
Yuce Tekol. <yucetekol@gmail.com>
:Project Website:
http://code.google.com/p/pyswip
Introduction
------------
PySWIP is a Python - SWI-Prolog bridge enabling to query SWI-Prolog in your Python programs. It features an (incomplete) SWI-Prolog foreign language interface, a utility class that makes it easy querying with Prolog and also a Pythonic interface.
Since PySWIP uses SWI-Prolog as a shared library and ctypes to access it, it doesn't require compilation to be installed.
Note that this version of PySWIP is slightly incompatible with 0.1.x versions.
Requirements:
-------------
* Python 2.3 and higher.
* ctypes 1.0 and higher.
* SWI-Prolog 5.6.x and higher (most probably other versions will also work).
* libpl as a shared library.
* Works on Linux and Win32, should work for all POSIX.
Example (Using Prolog):
-----------------------
>>> from pyswip import Prolog
>>> prolog = Prolog()
>>> prolog.assertz("father(michael,john)")
>>> prolog.assertz("father(michael,gina)")
>>> list(prolog.query("father(michael,X)"))
[{'X': 'john'}, {'X': 'gina'}]
>>> for soln in prolog.query("father(X,Y)"):
... print soln["X"], "is the father of", soln["Y"]
...
michael is the father of john
michael is the father of gina
Since version 0.1.3 of PySWIP, it is possible to register a Python function as a Prolog predicate through SWI-Prolog's foreign language interface.
Example (Foreign Functions):
----------------------------
from pyswip import Prolog, registerForeign
def hello(t):
print "Hello,", t
hello.arity = 1
registerForeign(hello)
prolog = Prolog()
prolog.assertz("father(michael,john)")
prolog.assertz("father(michael,gina)")
list(prolog.query("father(michael,X), hello(X)"))
Outputs:
Hello, john
Hello, gina
Since version 0.2, PySWIP contains a 'Pythonic' interface which allows writing predicates in pure Python (*Note that interface is experimental.*)
Example (Pythonic interface):
-----------------------------
from pyswip import Functor, Variable, Query
assertz = Functor("assertz", 2)
father = Functor("father", 2)
call(assertz(father("michael","john")))
call(assertz(father("michael","gina")))
X = Variable()
q = Query(father("michael",X))
while q.nextSolution():
print "Hello,", X.value
q.closeQuery()
Outputs:
Hello, john
Hello, gina
The core functionality of ``Prolog.query`` is based on Nathan Denny's public domain prolog.py found at http://www.ahsc.arizona.edu/~schcats/projects/docs/prolog-0.2.0.html
Install
-------
Please see ``INSTALL`` for detailed instructions.
