DIP19: Remove comma operator from D and provision better syntactic support for tuples

[bearophile]

Timon Gehr:

>> My bikeshed is colored one of these:
>>
>> (:1,2)
>> (|1,2)
>>
>
> At that point you might as well just use
>
> import std.typecons : q = tuple, Q = Tuple;
>
> Q!(int, int) foo(){
>     return q(1, 2);
> }
>
> If built-in tuples are not going to look like
>
> (1, 2)
>
> then imho we might as well leave them out,

But the banana syntax doesn't look bad:

(||)
(|1|)
(|1, 2|)
(|1, 2, 3|)

It's short enough, it's not visually noisy, it's simple enough to
type, it consistently avoids the problems with literals for
0-tuples and 1-tuples, and it's sufficiently intuitive once you
have seen it one time. It's just a bit longer to type than the
syntax with simple (), that has problems with the shorter tuples.

The now dead Fortress language used several similar syntaxes,
like (|...|), {|...|}, [|...|], etc.

Bye,
bearophile