transversal sum

[bearophile via Digitalmars-d-learn]

Marc Schütz:

>         int[][] input = new int[][2];
>         input[0] = [1, 2, 3, 4];
>         input[1] = [5, 6, 7, 8];
>         writeln(input);
>
>         auto sums = input
>                 .transposed
>                 .map!(a => a.sum);
>         writeln(sums);
>     }
>
> Output:
>
>     [[1, 2, 3, 4], [5, 6, 7, 8]]
>     [6, 8, 10, 12]

Jack specified:

> I have rectangular forward range of forward ranges (not arrays):

You "input" range is not just a Forward Range.

And by the way, your array literal can be written more simply 
like this:

int[][2] input = [[1, 2, 3, 4], [5, 6, 7, 8]];

Bye,
bearophile