foreach and retro

[Joseph Rushton Wakeling]

Hello all,

A problem with the retro function from std.range -- although it apparently 
operates on a bidirectional range, it fails when used with foreach requesting 
both value and index.  Running this code:

////////////////////////////////////////////////
import std.range, std.stdio;

void main()
{
      double[] a = [ 0, 1, 2, 3, 4, 5 ];

      foreach(i, x; retro(a))
            writeln(i, "\t", x);
}
////////////////////////////////////////////////

... results in an error: "cannot infer argument types".

Is there any reason why this should be so, or is it (as it seems to me) just a 
bug?

Thanks & best wishes,

    -- Joe