The ISO working group on the Prolog standard publishes a reference implementation of the part 3 draft which it should be possible to load as with any other Prolog file. http://www.sju.edu/~jhodgson/wg17/Drafts/DCGs/reference_implementation. Should you have difficulty finding it it is also in the git repository for GPJ. This should then provide support for part 3 of the standard. This currently does not work as it depends on some of the 2006 ISO extensions which we should have implemented for 0.3.0.