Why do std.traits use template foo(args...) instead of foo(alias arg) ?

[Low Functioning via Digitalmars-d-learn]

On Thursday, 18 December 2014 at 15:48:02 UTC, Mathias LANG wrote:
> An exemple being fullyQualifiedName:
> https://github.com/D-Programming-Language/phobos/blob/master/std/traits.d#L415
>
> I don't get this pattern. Is it documented somewhere ?

http://dlang.org/variadic-function-templates.html