Variadic grouping

[JS]

On Monday, 29 July 2013 at 15:02:13 UTC, Robert Clipsham wrote:
> On Monday, 29 July 2013 at 14:46:02 UTC, Robert Clipsham wrote:
>> You can achieve this like so:
>> ----
>> template Outer(T...) {
>>    template Inner(U...) {
>>        // Do something with T and U
>>    }
>> }
>> Outer!(a, b, c).Inner!(d, e, f);
>> ----
>>
>> You can see an example of it in action here (type tuple 
>> intersection):
>> https://github.com/mrmonday/misc/blob/master/misc/misc.d#L5
>>
>> Robert
>
> What would be more interesting would be to have the ability to
> have variadic variadics, so you could use something like:
> ----
> template Outer(T...) {
>      template Inner(U... ...) {
>          // Do something with T, U[0], U[1], U[2..$]
>      }
> }
> Outer!(a, b, c).Inner!(d, e, f).Inner!(g, h, i); // Etc
> ----
> Of course that raises the question of variadic variadic 
> variadics
> and variadic variadic variadic variadics and so on, and my
> proposed syntax is already silly............

I don't think so, this seems similar:

It would be cool if we could nest templates to get grouping


template tIF(alias cond)
{
     template tIF(alias T...)
     {
         template tIF(alias F...)
	{
	    ....
	}
}

then do

tIF!(cond)!(t1,t2,t3)!(f1,..,fn)

which would allow for a natural grouping of variadics. The 
notation may seem silly but only because it is not common.

which could have a short hand notation of

tIF!(cond; t1, t2, t3; f1, ..., fn);

(this way, if you can't keep track of your ';'s then you can use 
the long form)