From: Michael Fellinger <m.fellinger@...>
Date: 2007-11-28T21:53:24+09:00
Subject: Re: Ruby needs continuations...

[1,2,3].zip([4,5,6]).each{|a,b| p a => b}

also, ruby does have contiuations, check your facts (ri callcc) before
trying to complain, otherwise you will just appear as yet another
troll.

^ manveru

On 11/28/07, Just Another Victim of the Ambient Morality
<ihatespam@hotmail.com> wrote:
> Warning:  I don't really know what I'm talking about so if I make any
> mistakes in terminology, please try to correct me...
>
>
>     I've been doing a lot of Python programming and I've discovered that
> it's actually a very powerful language.  The language, itself, lacks any
> kind of elegance but it has all the power of Ruby and a little more
> performance.  It also has a richer set of libraries, although not in all
> areas, surprisingly.
>     One thing that Ruby should take from Python are continuations.  Python
> is moving away from list creation and version 3.0 functions will return
> Python iterators, implemented with continuations, instead of actual lists,
> since they are not used nearly as much as you might think.
>     The reason why I say that Ruby needs continuations is because they are
> more versatile than Ruby iterators.  The reason why I say _that_ is because
> you can make Ruby iterators with continuations but you can't make
> continuations with Ruby iterators.  This means that you can implement a
> continuation iterator and Object class can automatically define a Ruby
> iterator based on your continuation iterator.  After all, Ruby iterators are
> nice.  I'm surprised by how annoyed I am that Python for loops don't return
> a value...
>     One weakness of Ruby iterators that continuations don't have is parallel
> iteration.  If you have two containers that represent different aspects of
> the same things, it's difficult to iterate over both of them in Ruby.  In
> Python, you can do this:
>
>
> list1 = [1, 2, 3, 4]
> list2 = ['a', 'b', 'c', 'd']
>
> # Okay, Python is more wordy than I'd like
> # I could have just used zip() but you rarely need the list!
> for num, letter in itertools.izip(list1, list2):
>     # Do something with both numbers and letters
>     print num, letter
>     print
>
>
>     How would one do this in Ruby?  You can use .each_with_index and index
> the other list but that assumes that the other list is indexable, which only
> happens to be true of arrays but is not true in general.  I've thought about
> implementing some Ruby equivalent of zip() (or preferably izip()) and
> discovered that I can't do so without continuations.
>     ...Hence, my post.  I'm actually at odds with Pythonic philosophy.  The
> idea that there should only be one way to do things is ludicrous and a
> constant up hill battle.  One thing that Python does right is that it's not
> afraid to "steal" from other languages and that's the right attitude to
> have.  Adopt whatever is useful!
>     Python 3.0 looks like great language.  I'm hoping that Ruby 2.0 will be
> even better 'cause, frankly, Ruby is more fun to program in...
>     Thank you...
>
>
>
>
>