From: MonkeeSage <MonkeeSage@...>
Date: 2007-11-29T02:35:14+09:00
Subject: Re: Ruby needs continuations...

On Nov 28, 9:41 am, Charles Oliver Nutter <charles.nut...@sun.com>
wrote:
> MonkeeSage wrote:
> > You actually need a generator, which can be implemented with
> > continuations, but doesn't have to be (in 1.9 the generators are
> > implemented with threads -- have a look at generator.rb in 1.8 and 1.9
> > to see the differences). Using generators, you can implement izip (and
> > all of itertools if you'd like, though most of it already has
> > equivalent ruby solutions). Here is a pretty close translation of the
> > python given in the itertools docs:
>
> Ruby 1.9 also moves continuations out of core, but provides a form of
> bounded continuations (coroutines) that's possible to implement in JRuby:
>
> require 'fiber'
> f = Fiber.new { a = 1; while true; Fiber.yield a; a += 1; end }
> 5.times { puts f.resume }
>
> $ jruby -J-Djruby.compat.version=ruby1_9 fiber_example.rb
> 1
> 2
> 3
> 4
> 5
>
> Under JRuby, it's using a native thread per live Fiber, so it's heavier
> than in Ruby 1.9 which uses green threads. However they'll actually run
> in parallel on JRuby, so that's a benefit. JRuby also supports a thread
> pool in 1.1 that helps blunt the cost of spinning up native threads.
>
> - Charlie

I just tried the above izip function in jruby, but it only gave me two
iterations...

$ jruby test.rb
1
4
2
5

...hmm?

$ jruby -v
ruby 1.8.5 (2007-11-28 rev 3841) [i386-jruby1.0]

Regards,
Jordan