Impressed

[Stuart]

On Friday, 27 July 2012 at 00:10:31 UTC, Brad Anderson wrote:
> D uses ranges instead of iterators. You can read more about 
> them here: http://ddili.org/ders/d.en/ranges.html
>
> I find ranges to be a vast improvement over iterators 
> personally (I use iterators extensively in C++ for my job and 
> lament not having ranges regularly).
>
>
On Friday, 27 July 2012 at 00:17:21 UTC, H. S. Teoh wrote:
> D has something far superior: ranges.
>
> 	http://www.informit.com/articles/printerfriendly.aspx?p=1407357&rll=1
>
> Even better, they are completely implemented in the library. No
> unnecessary language bloat just to support them.

I'm not very well up on ranges. I understand the general [1 ... 
6] type of ranges, but I really don't see how custom range 
functions could be as useful as the Yield support in VB.NET. I 
mean, here's an example of an iterator in VB.NET:

    Public Function InfiniteSequence(StartValue As Int32, Step As 
Int32) As IEnumerable(Of Int32)
       Do
          Yield StartValue
          StartValue += Step
       Loop
    End Function

Usage:

    For Each N in InfiniteSequence(2, 2)
       ... do something with this sequence of even numbers ...
    Next

Notice how this function is written like a synchronous loop, yet 
yields a lazy-initialised infinite sequence of numbers. Granted, 
it's not a particularly useful example, but trust me: Iterators 
and Yield in .NET is *really* damn useful. I would go so far as 
to say it was one of the language's best features.

I may be wrong, but it looks like I'd have to code a new class - 
not to mention several specific functions and some kind of state 
variable - just to simulate this functionality in D. Can anyone 
clarify this for me?