Re: Prolog Ntriples Query Problem

On 01/03/2014 08:09 AM, atom meta wrote:
> Hello,
> 
> 
> I am trying to query an Ntriples file (.nt) on Prolog using the following
> code. It seems that I can load the data and consult it successfully.
> 
> But a problem occurs when I query the triples like rdf(X,Y,Z). It shows
> some kind of strange error saying that " Correct to: "rdf_db:rdf(X,Y,Z)"? ".
> 
> 
> PROLOG CODE:
> 
> 
> :- use_module(library(semweb/rdf_ntriples)).
> 
> rdf_load('schema-full.nt').

This _defines_ the predicate rdf_load/1.  If you want to _call_ something,
you normally define a predicate for this or you use the initialization
_directive_.  Thus:

:- use_module(library(semweb/rdf_db)).
:- use_module(library(semweb/rdf_ntriples)).

load_schema :-
	rdf_load('schema-full.nt').

And then in the command line:

	?- load_schema.
	<some message telling how many triples it loaded>
	true.

	?- rdf(S,P,O).
	S = ...

Or (in a file):

:- use_module(library(semweb/rdf_db)).
:- use_module(library(semweb/rdf_ntriples)).
:- initialization rdf_load('schema-full.nt').

Hope this helps.  You probably want to read `getting started'
(http://swi-prolog.org/pldoc/man?section=quickstart) and possibly
some beginners book or online tutorial.

	Success --- Jan