T[new]

[Sergey Gromov]

Mon, 10 Aug 2009 01:56:35 +0200, Michiel Helvensteijn wrote:

> Walter Bright wrote:
> 
>>> But I know, unique isn't easy to implement to fit all the use cases we'd
>>> like to solve. I'm just sharing a dream.
>> 
>> We explored unique at length, and trying to make it work would render
>> the rest of the language nearly unusably complex.
> 
> I've heard 'unique' mentioned on this group now and then. What does it mean
> in the context of programming languages?

Unique reference is a reference which is statically known to be the only
reference to the underlying data.  They have some interesting
properties:

- Modification of underlying data does not cause side effects
- Can be implicitly cast to immutable
- Can be implicitly cast to mutable

They prove to be rather tricky both to specify and to implement though.