On 9/7/2011 2:22, Invisible wrote:
 > then O(log N) new heap nodes get constructed.

Which, incidentally, is the same number of nodes you'd have to update in a 
mutable heap, too.

> But you don't ever have to worry about making one thread
> wait to update something until after the other thread has definitely
> finished using it.

That's not strictly true. It's entirely possible in modern processors that 
the pointer gets written and is visible to other processors before the data 
it points to gets flushed from the cache into main memory.

> Immutable arrays are great as super-fast lookup tables, but unless the data
> changes very infrequently, you end up needing mutable arrays. Immutable
> arrays just aren't all that useful.

Some of the google stuff is cool in that way. You can imagine you don't want 
to update the entire file that holds the entire web every time you scan a 
new document.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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