Error: closures are not yet supported in CTFE

[zeljkog via Digitalmars-d-learn]

I tried:

--
import std.stdio, std.algorithm;

auto unique(){
     bool[int] c;
     return (int a){
         if (a in c)
             return false;
         else{
             c[a] = true;
             return true;
         }
     };
}

void main()
{
     [1, 5, 5, 2, 1, 5, 6, 6].filter!(unique()).writeln;
}
--

And got:
Error: closures are not yet supported in CTFE

This works:

void main()
{
     auto x = unique();
     [1, 5, 5, 2, 1, 5, 6, 6].filter!x.writeln;
}

Is first version near?