define BinarySearch(A, value);
    lvars low = 1, high = length(A), mid;
    while low <= high do
        (low + high) div 2 -> mid;
        if A(mid) > value then
            mid - 1 -> high;
        elseif A(mid) < value then
            mid + 1 -> low;
        else
            return(mid);
        endif;
    endwhile;
    return("not_found");
enddefine;

/* Tests */
lvars A = {2 3 5 6 8};

BinarySearch(A, 4) =>
BinarySearch(A, 5) =>
BinarySearch(A, 8) =>