Prolog "BAGOF" command

[thors]

Hi all,

If anyboady is reading this, does someone have a clue on why the following fails ?

Directly, this works:

  ?- bagof(Y, legal(xplayer,Y), Moves).
Moves = [mark(1,1),mark(1,2),mark(1,3),mark(2,1),mark(2,2),mark(2,3),mark(3,1),mark(3,2),mark(3,3)] ? ;


But when defined:

retrieve_valid_states( _l ) :-
   bagof( _r, legal( _l , _r ), _m ).
  ?- retrieve_valid_states(X).
X = oplayer ? ;
X = xplayer ? ;

It "fails" by returning the incorrect values.

It's driving me slightly mad...

Well.. even a little more than slightly

[kristjanbb02]

It's kinda late now and you have probably noticed by now.

You are asking it for _l and it is just returning that correctly while you probably want _m like:


  ?- assert((retrieve_valid_states( _m ) :- bagof( _r, legal( _l , _r ), _m ))).
true ?
yes
  ?- retrieve_valid_states( X ).
X = [noop] ? ;
X = [mark(1,1),mark(1,2),mark(1,3),mark(2,1),mark(2,2),mark(2,3),mark(3,1),mark(3,2),mark(3,3)] ? ;
no


or more likely what you want is _m for specific role _l like:


  ?- assert((retrieve_valid_states( _l, _m ) :- bagof( _r, legal( _l , _r ), _m ))).
true ?
yes
  ?- retrieve_valid_states( xplayer, X ).
X = [mark(1,1),mark(1,2),mark(1,3),mark(2,1),mark(2,2),mark(2,3),mark(3,1),mark(3,2),mark(3,3)] ?
yes