Re: [ANN] Language::Prolog::Yaswi and DBD::Yaswi

Hi,

Ovid wrote:
> --- Salvador Fandi=F1o <[email protected]> wrote:
>=20
>>I have uploaded to CPAN version 0.07 of Language::Prolog::Yaswi,=20
>>  an interface to SWI-Prolog.
>>
>>I have also released DBD::Yaswi, an experimental DBI interface to=20
>>SWI-Prolog. I am not completely sure if this module is a real=20
>>improvement over the raw Language::Prolog::Yaswi... well,=20
>>comments are welcome!!!
>=20
>=20
> Hi Salvador,
>=20
> It's great to see stuff happening with this again!
>=20
> When I first tried to isntall DBD::Yaswi, I got: =20
> ...

DBD::Yaswi has to be registered on the DBI module, Tim Bunce (the=20
DBI author) have accepted to do it, but has not released a new=20
DBI yet.

You can modify your local DBI.pm:

Look for the registry hash $dbd_prefix_registry definition and=20
add an entry for DBD::Yaswi at the end as...

    yaswi_   =3D> { class =3D> 'DBD::Yaswi',          },

then it should work.



> Also, from the docs, it's not clear how to build a database or issue
> queries against it.  So let's say I want to find all X and Y that
> satisfy append/3, would I do something like this?



>   my $dbh =3D DBI->connect('dbi:Yaswi:user');
>   my $sth =3D $dbh->prepare(<<'END_PROLOG');
>     find [X,Y] where Z=3D[a,b,c,d], \
>     append([],X,X). \
>     append([W|X],Y,[W|Z]) :- append(X,Y,Z).
>   END_PROLOG
>=20
> From your docs and the tests, that doesn't seem right.
>=20
> Can I load a pre-existing prolog program, call assert, retract, etc?


You can freely mix calls to Language::Prolog::Yaswi and=20
DBD::Query, the only requirement is to not let queries open from=20
one module when calling the other (calling finish() on open=20
DBD::Yaswi queries or swi_cut on the Language::Prolog::Yaswi side).

There are new functions to consult files swi_consult() function=20
to consult files, i.e:

   swi_consult qw(foo, bar)
   swi_use_modules qw(foo, bar)

and the swi_inline function to consult inline modules.

   swi_inline <<PROLOG;
   append([], X, X).
   append([W|X],Y,[W|Z]) :- append(X,Y,Z).
   PROLOG


DBD::Yaswi can be extended via the multifile predicate=20
dbd:dbd_map_query/3.

I have included support for two simple operations, "find" and=20
"insert", just for experimentation, but others can be easyly=20
added, for example "consult":

   $db=3DDBI->connect('dbi:Yaswi:user')

   # and then, always after the connect call to ensure that
   # DBD::Yaswi has been loaded (or alternatively, loading
   # DBD::Yaswi explicitly):

   swi_inline << PROLOG;
   dbd:dbd_map_query(consult(X), consult(X), []).
   PROLOG

   $db->do('consult(foo)')

or even

   $sth_consult=3D$db->prepare('consult(?)')

   for (qw(foo bar doo) ) {
       $sth_consult->execute($_)
   }


I know module documentation is poor, but I have not really made=20
my mind yet about the right query language for DBD::Yaswi... and=20
anyway, the code is available and it is also a good example of=20
how to use Language::Prolog::Yaswi ;-)

Cheers,

   - Salvador