recursive_function(0) :- writeln('Done'), halt.
recursive_function(X) :-
% do something
writeln(X),
Y is X - 1,
recursive_function(Y).
?- recursive_function(2).
% 2
% 1
% Done
/* EXAMPLE: count to N starting at S */
count_to(N, S) :-
N =:= S,
writeln(N),
writeln('Done'),
halt.
count_to(N, S) :-
writeln(S),
X is S + 1,
count_to(N, X).
?- count_to(6, 2).
% 2
% 3
% 4
% 5
% 6
% Done
/* EXAMPLE: guess number loop */
guess_number :- loop(begin).
loop(begin) :-
writeln('Guess number: '),
read(Guess),
loop(Guess).
loop(42) :- writeln('Correct!').
loop(X) :-
X \= 42,
format('~w is not correct.', [X]), nl,
loop(begin).
?- guess_number.
% Guess number:
% |: 5.
% 5 is not correct.
% Guess number:
% |: 42.
% Correct!
% true .