Typed variadic template syntax?

[bearophile]

This is not an enhancement request, but it presents a potential 
enhancement.


This is C++11 code:

template<int... digits> struct value;

template<> struct value<> {
     static const int v = 0;
};

template<int first, int... rest> struct value<first, rest...> {
     static int const v = 10 * value<rest...>::v + first;
};



You can translate it to D like this:


enum isInt(T) = is(T == int);

template value(xs...) if (allSatisfy!(isInt, xs)) {
     static if (xs.length == 0)
         enum value = 0;
     else
         enum value = xs[0] + 10 * value!(xs[1 .. $]);
}


This D code:

template value(xs...) if (allSatisfy!(isInt, xs)) {


Is slower to compile than this D code:

template value(xs...) {


So we could allow D code like:

template value(int[] xs...) {


I think it could be faster than using "if (allSatisfy!(isInt, 
xs))" and it's nicer looking.

On the other hand I don't know how much common are template 
instantiations with values all of the same type (like all ints as 
in this case) in D code.

Opinions welcome.

Bye,
bearophile