Programmation déclarative - Q4B - 06/2012

slice(_, N1, N2, L2) :-
    N1 < 1,
    slice([], N1, N2, L2, 0), !.

slice([H|T], N1, N2, L2) :-
    length([H|T], Len),
    Len < N2,
    slice([], N1, N2, L2, 0), !.

slice(L1, N1, N2, L2) :-
    slice(L1, N1, N2, L2, 1).

slice([], _, _, [], _).

slice([H|T], N1, N2, L2, I) :-
    I >= N1,
    N2 >= I,
    J is I+1,
    slice(T, N1, N2, Tmp, J),
    append([H], Tmp, L2), !.

slice([_|T], N1, N2, L2, I) :-
    J is I+1,
    slice(T, N1, N2, L2, J), !.