Ruby needs continuations...

[Charles Oliver Nutter]

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

Could be a bug in generator; could you try it on a more recent release
(like 1.0.2 or 1.1b1) and report it if it's actually a problem?

http://jira.codehaus.org/browse/JRUBY

- Charlie

 

[MonkeeSage]

Could be a bug in generator; could you try it on a more recent release
(like 1.0.2 or 1.1b1) and report it if it's actually a problem?

http://jira.codehaus.org/browse/JRUBY

- Charlie

I downloaded the precompiled versions of 1.0.2 and 1.1b1 and both
displayed the same behavior. I'll submit a bug report.

Regards,
Jordan

 

[MonkeeSage]

I downloaded the precompiled versions of 1.0.2 and 1.1b1 and both
displayed the same behavior. I'll submit a bug report.

Regards,
Jordan

Bug #1635 [ http://jira.codehaus.org/browse/JRUBY-1635 ]

 

[Charles Oliver Nutter]

Bug #1635 [ http://jira.codehaus.org/browse/JRUBY-1635 ]

Cool, thanks. Now if you're really ambitious, maybe you can fix it

- Charlie

 

[MonkeeSage]

Bug #1635 [http://jira.codehaus.org/browse/JRUBY-1635]

Cool, thanks. Now if you're really ambitious, maybe you can fix it

- Charlie

Looks like somebody already beat me to it (with bells on!) [
http://jira.codehaus.org/browse/JRUBY-1635 ]; not that I'd have been
any help anyway.

Regards,
Jordan

 

[MonkeeSage]

========
require 'generator'
module Enumerable
def izip(*enumerables)
enumerables = [self] + enumerables
generators= enumerables.map { | enum |
Generator.new(enum)
}
whilegenerators[0].next?
result =generators.map { | gen |
gen.next
}
yield result
end
end
end
[1,2,3].izip([4,5,6]) { | x, y |
puts x, y
}
========
NB. generator.rb says thatgeneratorsare slow in 1.8.
Regards,
Jordan

Ps. The SyncEnumerator class from generator does the same thing as
izip:

SyncEnumerator.new([1,2,3], [4,5,6]).each { | x, y |
puts x, y
}

Thank you, MonkeeSage, this is exactly what I'm looking for!
It's interesting thatgeneratorsare slow enough to warn users about its
lack of speed! Do you know if it would be any faster implemented with
continuations? I'm surprised it's so slow considering Ruby employs green
threads...

Just for posterity, it should be noted that in this particular example
(and several others from itertools), you don't even need generators;
internal iterators work just fine...

def izip(*enums)
(enums[0].length).times { | i |
elems = enums.map { | enum |
enum
}
yield elems
}
end

izip([1,2,3], [4,5,6], [7,8,9]) { | elem |
p elem
}

Of course, you have to be wary about gotchas regarding the elements
being iterable and so forth; just thought it was worthy of mention
that this is possible with the built-in iteration construct, without
resorting to external iterators.

Regards,
Jordan