First of all let me apologize for posting in the wrong forum ... but I didn't find one for prolog... please redirect me if we have one ... and anyone's response if he/she knows the answer is appreciated. am trying to print the elements of a list.... one per line using a predicate of arity 1 .... which I am able to do with the code: Code: display_list([]) :- !, write('\nThe list is empty'). % handles empty list display_list([H|T]) :- write(' '), write(H), nl, display_list(T). The problem is: I want to have the sequence number of the list element in front of it: For example, 1 North 2 South 3 East 4 West I am not able to able to do that. The code I am writing is: Code: increment(X,Y) :- Y is X+1. display_list([]) :- !, write('\nThe list is empty'). display_list([H|T]) :- X = 0, increment(X,Y), write(Y),write(' '), write(H), nl, display_list(T). The output I get as expected is: 11 ?- display_list([north, south, east]). 1 north 1 south 1 east The list is empty true. Also I keep on getting this 'The list is empty' everytime the elements are exhausted and not only when the input list is empty ..... Please advice ...... Thanks
