Immutable and unique in C#

[Sönke Ludwig]

Just stumbled over this, which is describing a type system extension for
C# for race-free parallelism:

http://research.microsoft.com/pubs/170528/msr-tr-2012-79.pdf

Independent of this article I think D is currently missing out a lot by
omitting a proper unique type (a _proper_ library solution would be a
start, but I'm not sure if that can handle all details). It would make a
lot of the cases work that are currently simply not practical because of
loads of casts that are necessary.