Re: Dynamic Allocation seems to crash gprolog

[Leonardo B. Lopes]

I apologize for that. The whole code is actually almost 200 lines, and I
thought that I had a closed set of predicates. Here are the missing
predicates and an example query that fails:

/* Leaf */ 
leaf(Node) :-   _ is_parent Node, \+ Node is_parent _2.
         
/* Set are the
children on Node */ 
:- op(500,xfx,'areChildrenOf'). 
[] areChildrenOf Node :- leaf(Node).
Set areChildrenOf Node :-   setof(Child,Node is_parent Child,Set).

printTree(X) :- write('$'),
                C areChildrenOf X,
                printChildren(C),
                write('^').

printChildren([]):- !.
printChildren([H|T]) :-         printTree(H),
                                printChildren(T), !.

I attached a small terminal session that shows how the code fails.

> BTW the current stable version is 1.2.8 and fixes some bugs with dynamic 
> code. see
> http://gprolog.inria.fr for more information on how to download it...

This is important info! Thanks for the heads up. I didn't know what had
changed between versions, so I wasn't sure if upgrading would solve my
problem. If I could make a suggestion, it would be helpful to have a
change log specifying what has changed from one version to the next...
Maybe it is there but I couldn't find it. So I'll upgrade and see if the
problem persists. I'll get back to you later. Thanks for your help!

Leo.

> 
> 
> 
> "Leonardo B. Lopes" wrote:
> > 
> > Dear Friends:
> > 
> >         I have this little routine which does a search over special trees.
> > I would like to delete the tree once it is no longer useful, but this code
> > seems to crash gprolog. Is there something I'm doing wrong?
> > 
> > :- dynamic(parent/2,root/1,is_parent/2,is_root/1).
> > 
> > :- op(500,xfx,(is_parent)).
> > 
> > :- op(500,xfx,'has_children').
> > X has_children 0 :-     leaf(X).
> > X has_children Y :- setof(Children, X is_parent Children, Set),
> >                                         length(Set,Y).
> > 
> > printTree(X) :- write('$'),
> >                                 C areChildrenOf X,
> >                                 printChildren(C),
> >                                 write('^').
> > 
> > createBalancedTree([],_):- !.
> > createBalancedTree([RootDegree|DegreeList],Tree) :-
> >         new_atom(Tree),
> >         for(_,1,RootDegree),
> >                 createBalancedTree(DegreeList,Child),
> >                 asserta( Tree is_parent Child),
> >         Tree has_children RootDegree.
> > 
> > deleteTree(Tree) :-
> >         Tree is_parent X,
> >         retract(Tree is_parent X),
> >         deleteTree(X).
> > 
> > Also, any other trees previously defined also get deleted when I use
> > deleteTree. BTW, I'm using gprolog 1.2.1.
> > 
> > Appreciate any help!
> > Leo.
> > 
> > ========================================================================
> > Leonardo B. Lopes                                       address@hidden
> > Ph.D. Student                                              (847)491-8470
> > IEMS - Northwestern University              http://www.iems.nwu.edu/~leo
> > 
> 
> 
> -- 
> Daniel Diaz   address@hidden
> http://pauillac.inria.fr/~diaz
> gprolog --version 2>&1 | sed -n -e 's/By //p'
> 

========================================================================
Leonardo B. Lopes                                       address@hidden 
Ph.D. Student                                              (847)491-8470
IEMS - Northwestern University              http://www.iems.nwu.edu/~leo

tree.pl
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gprolog.output
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