Does D have "structural sharing" of immutable collections?

[Roman D. Boiko]

On Wednesday, 23 May 2012 at 21:13:48 UTC, Andrei Alexandrescu 
wrote:
> Okasaki put together the ultimate work on immutable data 
> structures. I have plans to add immutable collections to D 
> containers once I sort out the allocators matter. 
> Unfortunately, I find myself gasping for time so the news that 
> you are working on such are awesome. I suggest you to absorb 
> the approach taken by ranges and (however incomplete it looks 
> at the moment) std.container, and build on such.
>
> Andrei

I would appreciate critics and feedback once I start. The most 
difficult part is conceptual. Range primitives don't fit. I'm 
trying to invent something as good as ranges are for mutable 
data, but I don't feel that I'm qualified enough to get it right 
without help.

The end goal is to have something as easy to work with as 
collections of Scala or F# (I don't know Haskell), and, of 
course, efficient.