From: Alexander Schofield <pcs3@...>
Date: 2002-02-06T07:41:01+09:00
Subject: Re: Call/CC and Ruby iterators.

> On Wed, Feb 06, 2002 at 03:20:46AM +0900, Thaddeus L Olczyk wrote:
> > Reading about call/cc in Scheme I get the impression that it is very
> > like Ruby's iterators.
> > Not being an expert in others I thought I would ask.

call/cc is not really used for simple iteration, but more for when you
want some kind of concurrent execution (think threads-- except you have
to manually construct a system).  Lisp and Scheme typically iterate by
mapping functions to lists (which may have been filtered).  Here's a
simple example in CL:

CL-USER 8 > l
(1 2 3 4 5 6 7 8)

CL-USER 9 > (let ((odds (remove-if-not #'oddp l)))
              (mapcar (lambda (x) (/ x 2)) odds))

(1/2 3/2 5/2 7/2)

HTH
-- 
Alexander Schofield