Nulls

[Brian Goetz]

> I only bring up the others because so many people are worried that the
> extra Optional object will never ever be optimized away and will slow
> everything down.

The "extra object" argument here is mostly a red herring.  There is so 
much work going on to set up the iterators and such, that one more 
object *per pipeline* is noise.  An object per element, sure, that's a 
big deal.  But to set up a pipeline you're probably already allocating a 
few objects per pipeline stage -- the Op object, an Iterator or a Sink, 
etc.

If you're doing a parallel decomposition you're creating log(n) FJtasks 
and such.  Again, another object at the end is noise.