predicate that returns a list of positions of given Subterm

[LordHelmet666]

Can someone help me with this?


I have a predicate that returns to me the number of times
the Subterm occurs, but I need it to return to me a list of
the positions it occurs at.


*******************WHAT I HAVE*******************
position(_,[],0).
position(X,[X|L],N) :- position(X,L,M), N is M+1.
position(X,[Y|L],N) :- not(X=Y), position(X,L,N).
*************************************************
?-position(a, [a,b,c,a,d,a,e,a,f], P).

P=4
*************************************************



=================WHAT I NEED=====================
CODE FOR THE FUNCTION TO RETURN LIST OF POSITIONS
=================================================
?-position(a, [a,b,c,a,d,a,e,a,f], P).

%Need the code for this version


%This is what it is supposed to return.

P = [1,4,6,8]
=================================================


Any help would be extremely appreciated.

Thanks

-LordHelmet666

 

[joel76]

*******************WHAT I HAVE*******************
position(_,[],0).
position(X,[X|L],N) :- position(X,L,M), N is M+1.
position(X,[Y|L],N) :- not(X=Y), position(X,L,N).
*************************************************
To do what you want, you need un argument which count the number of the loop. Every time the comparaison succeeds, you memorize it in a list.