:- module(fibonacci, [fib/2]).

fib(0, 0) :- !.
fib(1, 1) :- !.
fib(N, F) :-
    N > 1,
    N1 is N - 1,
    N2 is N - 2,
    fib(N1, F1),
    fib(N2, F2),
    F is F1 + F2.

:- fib(10, F), write(F), nl.
:- halt.