Is this function pure?

[Frits van Bommel]

Bill Baxter wrote:
> The 'fast allocation' claim may be true of generational GCs or other 
> fancy GCs, but D currently has a mark&sweep type.

Yes, AFAIK the 'fast allocation' is mostly true of garbage collectors 
that move objects that aren't collected, since they have all free memory 
in a contiguous block and can just increment a pointer.

However, I can see /deallocation/ being faster with a GC since the cost 
of explicit deallocation isn't just limited to the free/delete call; it 
also often incurs the cost of tracking *when* to call them (which often 
means using things like reference counts, which in a multithreaded app 
need a mutex...).
Also, a GC gets to postpone memory deallocation until it's actually 
needed, which can sometimes mean they don't have to do it at all (if 
your program doesn't allocate all that much).

Note: I'm not saying using a GC is necessarily faster (since I don't 
have the numbers), just that I can see how it *could* be.

Of course, there's also the programmer convenience factor :).