From: Alex Shinn <foof@...>
Date: 2002-02-06T10:41:30+09:00
Subject: Re: Call/CC and Ruby iterators.

>>>>> "Thaddeus" == Thaddeus L Olczyk <olczyk@interaccess.com> writes:

    Thaddeus> Reading about call/cc in Scheme I get the impression that
    Thaddeus> it is very like Ruby's iterators.  Not being an expert in
    Thaddeus> others I thought I would ask.

Yes.  And bumblebees are like jumbo jets :)

Iterators loop over each element of a class.  However you define them
they will go from start to end and you can't interrupt them in the
middle.

Continuations capture the current lexical environment and program
location and wrap it up as a first class procedure.  You can then store
it away and call it later at any point to achieve non-linear control
flow.  Continuations make it easy to implement things like exception
handling and cooperative threading.

Of course, Ruby supports closures as first class objects so you could
probably get something continuation-like in Ruby - just don't try it
with iterators.  And continuations lose a lot without proper tail
recursion.

-- 
Alex
def y(&le)lambda{|f|f.call(f)}.call(lambda{|f|le.call(lambda{|*x|(f.call(
f)).call(*x)})})end