Path: csiph.com!aioe.org!.POSTED!not-for-mail
From: Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm>
Newsgroups: comp.lang.forth
Subject: Re: BEGIN WHILE UNTIL THEN
Date: Fri, 8 Jan 2016 10:11:53 -0500
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On Fri, 8 Jan 2016 12:36:25 +1100
"HAA" <someone@microsoft.com> wrote:

> Rod Pemberton wrote:

> > Since the BEGIN-UNTIL now exits for two
> > conditions, you must determine which condition caused
> > it to exit, afterwards.
> > ...  
> 
> This is the problem ANS WHILE was designed to solve.  It lets you
> exit the loop at different points avoiding the need to test (again)
> which condition caused the exit e.g.
> 
> ...
> 
> The topic is discussed by Brodie/Moore in 'Thinking FORTH' Chapter
> 8 ...
> 
> "The value is that you get simpler programs.  And it costs nothing."

It doesn't cost nothing.  The branching clearly increases.

My understanding is that modern processors are good with
single loops with a backwards branch.  That might be
somewhat simplistic or out of date, but the point of
branching complexity not being good remains.


Rod Pemberton