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From: dave@PRC.Unisys.COM (David Lee Matuszek)
Newsgroups: comp.lang.misc
Subject: Re: NOT Educating FORTRAN programmers to use C
Message-ID: <12576@burdvax.PRC.Unisys.COM>
Date: 19 Jan 90 21:06:30 GMT
References: <15623@haddock.ima.isc.com> <8960003@hpfcso.HP.COM> <1990Jan17.042608.447@esegue.segue.boston.ma.us> <12950@cbnewsc.ATT.COM>
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In article <12950@cbnewsc.ATT.COM> res@cbnewsc.ATT.COM (Rich Strebendt) writes:

>  Also, it should also be kept in mind that,
>while it is fun to figure out how to optimize very exotic constructs,
>the most frequently occuring construct in any programming language is
>equivalent to the construct x += 1

Er, not quite *any* programming language.  I have been programming
professionally in Prolog for the last five years, and I need to do
this sort of thing maybe once or twice a year.

BTW, here's how to do it:

	increment(Variable) :-
		retract(value(Variable, OldValue)),
		NewValue is OldValue + 1,
		assert(value(Variable, NewValue)).

	..., increment(x), ...

but as this makes two modifications to the database and is therefore
pretty expensive (not to mention poor style), you don't want to do it
too often.

Moral:  "Toto, I don't think we're in Kansas anymore."

-- Dave Matuszek (dave@prc.unisys.com)
-- Unisys Corp. / Paoli Research Center / PO Box 517 / Paoli PA  19301
-- Any resemblance between my opinions and those of my employer is improbable.
  << Those who fail to learn from Unix are doomed to repeat it. >>