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Date: Sat, 16 Feb 2002 09:10:18 -0500
From: "Eric S. Raymond" <esr@thyrsus.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Jeff Garzik <jgarzik@mandrakesoft.com>, Dave Jones <davej@suse.de>,
        Arjan van de Ven <arjan@pc1-camc5-0-cust78.cam.cable.ntl.com>,
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Subject: Re: Disgusted with kbuild developers
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Alan Cox <alan@lxorguk.ukuu.org.uk>:
> The graph tells you that. The only interesting case I could find is the
> negation one - some rules are  A conflicts with B which makes the UI side
> much more fun

That's right.  This is a CML2 require/prohibit construct.  CML1 cannot
express this, and it's essential for side-effect forcing to work.  Jeff's
observation about being tempted to introduce a `require' turns out actually 
to be equivalent once you see how both problems generalize.

You can't deduce these constraints from graph analysis, because they're 
not implicit in the if/then tree structure that is the only thing CML1
knows about.

Jeff and Alan have now almost caught up to where I was two years ago when
I realized the CMl1 formalism was inadequate.

This is going in the FAQ.
-- 
		<a href="http://www.tuxedo.org/~esr/">Eric S. Raymond</a>
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