Immutable and unique in C#

[Walter Bright]

On 11/11/2012 10:59 AM, Sönke Ludwig wrote:
> However, I have to admit that without actually trying it and seeing how
> usable it is first hand, it's difficult to tell how usable it is in
> practice (e.g. because D functions have to be explicitly tagged 'pure'
> for the recovery to work).

With purity, transitive immutability, and transitive sharing, D already is quite 
a long way down the road. But we can go further, as currently new() and pure 
functions are not exploited for their implicit casting ability.

For example,

     struct S { int x; }
     ...
     shared S* s = new S();

can be made to work, as can:

     pure S* foo(S* s);
     shared S* s = foo(new S());

I'm not convinced that adding a "unique" qualifier is strictly necessary.