Split a list in half

Question

I need to define divide so that List [1,2,3,4,5] divides into:

a = [1,2,3}

b = [4,5]

I\'m getting an error that says \"

Answer 1

Another answer, uses Backtracking a lot, isn't very performant, though. append and length are assumed to be predefined:

divide(A,B,C):-
    append(B,C,A),
    length(B,B_Length),
    length(C,C_Length),
    (B_Length = C_Length;
        B_Length =:= C_Length +1).

Oh, sorry, just have seen that this is sort of a rephrasing of the answer from Philip Whitehouse.