Prolog tail call optimization problem

stack_workspace.org

Simple phase_step predicate.

phase_step(I, O) :- O is I + 1.
step_n(0, I, I).
step_n(N, In, Out) :-
    prolog_current_frame(Z), format('~w ', Z),
    N > 0, N1 is N -1, phase_step(In, T),
    step_n(N1, T, Out).
:- step_n(10, 1, X).

362 362 362 362 362 362 362 362 362 362

Same stack frame.

My use case, a complicated phase_step predicate.

% pattern for the nth digit mth-coeffcient
digit_m(N, M, D) :-
    divmod(M, N, Q, _),  divmod(Q, 4, _, C),
    (C = 0, D = 0; C = 1, D = 1; C = 2, D = 0; C = 3, D = -1).

calculate_digit_n(N, In, D) :-
    calculate_digit_n_(N, In, D, 1, 0).
calculate_digit_n_(_, [], D, _, Acc) :- D1 is abs(Acc), divmod(D1, 10, _, D).
calculate_digit_n_(N, [I | Is], D, M, Acc) :-
    digit_m(N, M, C), P is C*I, M1 is M+1, Acc1 is Acc+P,
    calculate_digit_n_(N, Is, D, M1, Acc1).

phase_step(In, Out) :-
    length(In, L), L1 is L + 1, phase_step_(In, Out, L1, 1, []).
phase_step_(_, Out, L, L, Acc) :- reverse(Out, Acc).
phase_step_(In, Out, L, N, Acc) :-
    N < L, calculate_digit_n(N, In, D), N1 is N + 1,
    phase_step_(In, Out, L, N1, [D | Acc]).

step_n(0, I, I).
step_n(N, In, Out) :-
    prolog_current_frame(Fr), format('~w ', Fr),
    N > 0, N1 is N - 1, phase_step(In, T),
    step_n(N1, T, Out).
:- step_n(10, [1, 2, 3, 4, 5, 6, 7, 8], X).

362 3183 6004 8825 11646 14467 17288 20109 22930 25751

Different stack frame every time.