Example Rev

Jan Burse, created Oct 19. 2018
/**
* Prolog code for the deterministic tracing example.
*
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rev(X, Y) :-
rev(X, [], Y).
rev([], X, X).
rev([X|Y], Z, T) :-
rev(Y, [X|Z], T).
% ?- rev([1,2,3], X).
% X = [3,2,1]
% ?- trace.
% Yes
% ?- rev([1,2,3], X).
% 0 Call rev([1,2,3], X) ?
% 1 Call rev([1,2,3], [], X) ?
% 2 Call rev([2,3], [1], X) ?
% 3 Call rev([3], [2,1], X) ?
% 4 Call rev([], [3,2,1], X) ?
% 4 Exit rev([], [3,2,1], [3,2,1]) ?
% 3 Exit rev([3], [2,1], [3,2,1]) ?
% 2 Exit rev([2,3], [1], [3,2,1]) ?
% 1 Exit rev([1,2,3], [], [3,2,1]) ?
% 0 Exit rev([1,2,3], [3,2,1]) ?
% X = [3,2,1]

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