Make a type tuple from an array

[Artur Skawina via Digitalmars-d-learn]

On 04/10/15 17:36, John Colvin via Digitalmars-d-learn wrote:
> On Friday, 10 April 2015 at 15:13:54 UTC, Marc Schütz wrote:
>> Is there a way to turn an array (known at compile time) into a TypeTuple? 

> For input ranges in general:
> 
> import std.range : isInputRange;
> 
> template TypeTupleOf(TL...)
>     if (TL.length == 1 && isInputRange!(typeof(TL[0])))
> {
>     import std.typetuple : TT = TypeTuple;
>     enum r = TL[0];
>     static if (r.empty)
>         alias TypeTupleOf = TT!();
>     else
>     {
>         enum f = r.front;
>         alias TypeTupleOf = TT!(
>             f,
>             TypeTupleOf!(
>                 { auto tmp = r; tmp.popFront(); return tmp; }()
>                 )
>             );
>     }
> }

Neat, but very unreadable...

   import std.array, std.range : isInputRange, dropOne;

   template TypeTupleOf(alias R) if (isInputRange!(typeof(R))) {
      import std.typetuple : TT = TypeTuple;
      static if (R.empty)
         alias TypeTupleOf = TT!();
      else
         alias TypeTupleOf = TT!(R.front(), TypeTupleOf!(R.dropOne()));
   }

artur