Pure functions in D

[Denis Koroskin]

On Tue, 23 Sep 2008 02:24:10 +0400, Walter Bright  
<newshound1 at digitalmars.com> wrote:

> bearophile wrote:
>>> They can be hot swapped (meaning replaced at runtime), because they
>>> do not rely on any global initialization or termination state.<
>>  This sounds true and interesting, but what can it be used/useful for?
>
> I've heard mention many times that languages like Erlang allow hot  
> swapping meaning the software can be upgraded without bringing the  
> system to a halt first.

Yes, Java has some support of hot-swapping, too.

Imagine you have a MMORPG server. Applying a patch or adding some  
additional content is a daily event. Doing so without disconnecting the  
people (especially if there are thousands of player online) is desirable  
but hardly available in C/C++.