Language::XSB 0.14

Language::XSB is a Perl module that allows you to use XSB from Perl.

SYNOPSIS

use Language::XSB :query;
use Language::Prolog::Types::overload;
use Language::Prolog::Sugar vars=>[qw(X Y Z)],
functors=>{equal => =},
functors=>[qw(is)],
chains=>{plus => +,
orn => ;};

xsb_set_query( equal(X, 34),
equal(Y, -12),
is(Z, plus( X,
Y,
1000 )));

while(xsb_next()) {
printf("X=%d, Y=%d, Z=%dn",
xsb_var(X), xsb_var(Y), xsb_var(Z))
}

print join("n", xsb_find_all(orn(equal(X, 27),
equal(X, 45)), X)), "n";

ABSTRACT

Language::XSB provides a bidirectional interface to XSB (http://xsb.sourceforge.net/).

From the XSB manual:

XSB is a research-oriented Logic Programming and Deductive
Database System developed at SUNY Stony Brook. In addition to
providing all the functionality of Prolog, it contains
features not usually found in Logic Programming Systems such
as evaluation according to the Well Founded Semantics through
full SLG resolution, constraint handling for tabled programs,
a compiled HiLog implementation, unification factoring and
interfaces to other systems such as ODBC, C, Java, Perl, and
Oracle

This package implements a bidirectional interface to XSB, thats means that Perl can call XSB that can call Perl back that can call XSB again, etc.:

Perl -> XSB -> Perl -> XSB -> ...

(Unfortunately, you have to start from Perl, XSB->Perl->... is not possible.)
The interface to XSB is based on the objects created by the package Language::Prolog::Types. You can also use Language::Prolog::Sugar package, a front end for the types package to improve the look of your source (just some syntactic sugar).

To make queries to XSB you have to set first the query term with the function xsb_set_query, and then use xsb_next and xsb_result to iterate over it and get the results back.

Only one query can be open at any time, unless when Perl is called back from XSB, but then the old query is not visible.