Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!gegeweb.org!news.snarked.org!newsfeed.news.ucla.edu!news.usc.edu!news.isi.edu!usenet
From: tar@sevak.isi.edu (Thomas A. Russ)
Newsgroups: comp.lang.lisp,comp.lang.python,alt.usage.english
Subject: Re: English Idiom in Unix: Directory Recursively
Date: 17 May 2011 23:42:20 -0700
Organization: USC Information Sciences Institute
Lines: 20
Sender: tar@blackcat.isi.edu
Message-ID: <ymir57wldbn.fsf@blackcat.isi.edu>
References: <c159267e-22f9-4821-a70d-2f111cc35de4@f31g2000pri.googlegroups.com> <iqvj9f$3ci$6@dont-email.me> <87aaekoab7.fsf@kuiper.lan.informatimago.com>
NNTP-Posting-Host: blackcat.isi.edu
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2
Xref: x330-a1.tempe.blueboxinc.net comp.lang.lisp:3501 comp.lang.python:5670

"Pascal J. Bourguignon" <pjb@informatimago.com> writes:

> Roland Hutchinson <my.spamtrap@verizon.net> writes:

> > Tail recursion  can always be turned into an iteration when it is
> > executed.  
> 
> All recursions can be turned into iterations, before execution.

True, but only by simulating the call stack in the iterative code.  To
my mind that isn't really an iterative algorithm anymore if it ends up
simulating the call stack.

Tree walks are the canonical example of what can't be done in an
iterative fashion without the addition of an explicitly managed stack



-- 
Thomas A. Russ,  USC/Information Sciences Institute