Hi Alex, thanks for quick reply
On Wed, Feb 9, 2022 at 8:13 AM Alexander Burger <a...@software-lab.de> wrote:
>
> > Is the reference documentation incorrect?
>
> No, but it seems that you looked at the reference for pil21.
>
> The syntax for calling Lisp expressions in Pilog was made a little
> friendlier in
> pil21, by binding variables directly, so that calling '->' is normally not
> needed any more.
>
>
Ok, thanks for the clarification
> > but I cannot get an answer for the inverse query:
> >
> > : (? (factorial @X 120))
> > -> NIL
>
> This is another issue. This Pilog version of factorial cannot do reverse
> lookup,
> as it calculate numeric values via Lisp calls.
>
Ok, I suspected that but is there any way to do arithmetic in pilog? My
understanding is you have to use picolisp for arithmetic
How should be declared factorial primitive to be compatible with reverse
lookup?
> > Also I would like to know if pilog unification deals with compound
> > predicates, I mean, in prolog you can write:
> >
> > p(a).
> > p(R(y)).
> > ? p( X )
> > X=a
> > X=R(y)
> >
> > Querying for values of X veryfing a p predicate. How can you get that in
> > pilog?
>
> Yes, you can do that, but not in that direct syntax.
>
> You could take a look at how 'not', 'call' or 'or' are implemented in
> @lib/pilog.l for examples.
>
>
Ok, I'm doing, I'll post any question about it
May you tell me what syntax is the right one for prolog primitives
translated to pilog?
prolog pilog
p(r(b)). (be p (r (b))) -(1)- or
(be p ((r (b)))) -(2)- or
(be p ((r b))) -(3)-
p(z(a),b) (be p ((z a) b)) -(1)- or
(be p ((z (a)) b)) -(2)-
what is supposed to mean (be p (r (b))) if anything?
May you explain the estructure of a pilog environment (and the use of unify
function) and how pilog clauses are converted to property lists? what
kind of unification algorithm uses pilog? maybe in a PilCon session
thanks and best regards
