On 18.03.2010, at 16:30, Ralph Johnson wrote:
> 
> On 3/18/10, Bert Freudenberg <bert at freudenbergs.de> wrote:
> 
>> With true immutables you can start developing in a mixed object/functional style, which would allow interesting optimizations, e.g. for concurrency, memoization etc.
> 
> I've developed in a mixed object/functional style for years, and I
> think a lot of other people do, too.   You don't need language support
> for this, though I expect it would be helpful.  It makes concurrency
> and distributed programming easier, and is important when you are
> dealing with databases.  Eric Evans calls this "Value Object" in his
> book "Domain Driven Design".
> 
> -Ralph Johnson

Right, the style is possible without VM support in your own subsystem. But being able to *guarantee* immutability would allow to generalize this beyond your own special-purpose code. And possibly it would enable further VM-level optimizations.

- Bert -