From: Charles Oliver Nutter <charles.nutter@...>
Date: 2008-12-06T04:57:24+09:00
Subject: [ruby-core:20387] Re: Leave my open classes alone (was  Behavior: autoload calls rb_require()  directly)

Brent Roman wrote:
> Paul,
> 
> As we all know, Ruby
> Integers are 32-bits or 64-bits wide, but Fixnums are somewhat smaller.
> They get transparently promoted by Bignums as needed.
> Similarly, a 64-bit VM could define SmallFloats.  These would be a floats
> few bits
> short of 64-bits that are promoted to a full Floats as needed.
> This video presentation of Allan Ottis at RubyConf 2008 explains
> what gemstone did in their proprietary MagLev VM:

There's a lot of interest in adding value types and tagged numerics to 
the JVM, and I believe some work has already started on it. Currently 
JRuby doesn't even have tagged Fixnums, though the speed of allocation 
and young gen GC on the JVM makes up for it (we're still comfortably 
faster than 1.9 on numeric benchmarks). However long term we'll need 
them to really show full-speed arithmetic on the JVM, and since several 
languages have said the same thing, they're likely to be added.

Here's an article by John Rose, one of the folks responsible for 
Hotspot's optimizing JIT:

http://blogs.sun.com/jrose/entry/fixnums_in_the_vm

As with all features, John never makes it sound particularly difficult 
to add. By this time next year, the JVM may have fixnums, fast dynamic 
dispatch, tail calls, continuations, value types/tuples, interface 
injection, and a whole lot more.

- Charlie