auto ndarray(size_t N, Range)(auto ref Slice!(N, Range) slice)
{
    import std.array: array;
    static if (N == 1)
    {
        return slice.array;
    }
    else
    {
        import std.algorithm.iteration: map;
        return slice.map!(a => ndarray(a)).array;
    }
}

import std.range: iota;
auto ar = ndarray(12.iota.sliced(3, 4));
static assert(is(typeof(ar) == int[][]));
assert(ar == [[0, 1, 2, 3], [4, 5, 6, 7], [8, 9, 10, 11]]);