What is the closest to ConcurrentHashMap and NavigableMap in Java?

[Jacek Furmankiewicz]

No, we didn't decide to migrate to D. Java is working out fine 
for us.

I am however always interested in what is out there, 'cause you 
never know if there may not be a better solution.

And from what I've seen so far I really like D in terms of pure 
language features.

Go is cool too, but it has made some choices which to me are 
questionable (error codes instead of exceptions, lack of 
templates/generics).

Coupled with vibe.d, dub, etc. I see some really interesting 
stuff going on in the D community that seems to have been greatly 
under the radar.

Definitely plan to spend more time with D on my own, even if I 
cannot use it at work.