Challenge Tuples

[Nick Treleaven]

On Saturday, 27 April 2024 at 11:55:58 UTC, Basile B. wrote:
> Here's [STYX](https://gitlab.com/styx-lang/styx) solution:
>
>
>     function sum[T,U](U u): u32

I think you meant `: T`.

>     {
>         var T result;
>         foreach const e in u do
>             if echo(is, e, T) do
>                 result += e;
>             else do
>                 result += sum![T](e);
>         return result;
>     }
>
>     function main(): s32
>     {
>         assert((1, 2, 3, [1, 3], 5).sum![u32]() == 15);
>         return 0;
>     }

Mostly equivalent D:
```d
R sum(R = long, T)(T v)
{
     R r;
     foreach (e; v)
     {
         static if (is(typeof(e) == int))
             r += e;
         else
             r += sum!R(e);
     }
     return r;
}

void main()
{
     import std;
     assert(tuple(1, 2, 3, [1, 3], 5).sum == 15);
}
```