ian-andrich / PythonPengines

A Python interface to the Prolog pengines library. Makes it exceedingly easy to call out to SWI-Prolog within Python!

Python Pengines

This is a module for interfacing python with the Prolog Pengines knowledge base.

API

Create a basic run pengine server script, and run it with swipl.

:- use_module(library(http/thread_httpd)).
:- use_module(library(http/http_dispatch)).
:- use_module(library(pengines)).

server(Port) :- http_server(http_dispatch, [port(Port)]).

:- server(4242).

Initialize a basic PengineBuilder

from pengines.Builder import PengineBuilder
from pengines.Pengine import Pengine

pengine_builder = PengineBuilder(urlserver="http://localhost:4242")

Create the pengine querying object.

pengine = Pengine(builder=pengine_builder)

Make your query -- note the lack of ending period -- Pengine performs the query like 'ask(member(X, [1,2,3], [])).'

query = "member(X, [1,2,3])"
pengine.doAsk(pengine.ask(query))
print(pengine.currentQuery.availProofs)

Iterate through the proofs like this:

while pengine.currentQuery.hasMore:
    pengine.doNext(pengine.currentQuery)
    print(pengine.currentQuery.availProofs)

Alternatively, the query can be provided to the builder:

src_pl = "foo(a).\nfoo(b).\nfoo(c)."
query = "foo(X)"
factory = PengineBuilder(urlserver="http://localhost:4242", destroy=False, srctext=src_pl, ask=query)
pengine = Pengine(builder=factory)
results = pengine.currentQuery.availProofs
print(results)

prologterms library

The python library prologterms aims to make it easier to construct prolog programs and query terms from within python.

For an example of how to use prologterms in conjunction with pengines, see:

https://pypi.org/project/prologterms/

from pengines.Builder import PengineBuilder
from pengines.Pengine import Pengine
from prologterms import TermGenerator, PrologRenderer, Program, Var

P = TermGenerator()
X = Var('X')
Y = Var('Y')
Z = Var('Z')
R = PrologRenderer()

p = Program(
    P.ancestor(X,Y) <= (P.parent(X,Z), P.ancestor(Z,Y)),
    P.ancestor(X,Y) <= P.parent(X,Y),
    P.parent('a','b'),
    P.parent('b','c'),
    P.parent('c','d')
)

q = P.ancestor(X,Y)

factory = PengineBuilder(urlserver="http://localhost:4242",
                         srctext=R.render(p),
                         ask=R.render(q))
pengine = Pengine(builder=factory, debug=True)
while pengine.currentQuery.hasMore:
    pengine.doNext(pengine.currentQuery)
for p in pengine.currentQuery.availProofs:
    print('{} <- {}'.format(p[X.name], p[Y.name]))