🚀 go-pugleaf

In article <1396@quintus.UUCP> dave@quintus.UUCP (David Bowen) writes:
>...  If the Prolog implementation isn't able to spot the determinacy
>it has to keep backtracking information around indefinitely, which can waste
>arbitrary amounts of space.  The simplest way to correct this is to add cuts at
>all appropriate places....

     This reminds me of something I've been wondering about for
a while.  Built-in "if-then-else" and "case" constructs are
often touted as a way of getting around using cuts.  What is the
current wisdom about this?  I know that not all uses of cut can
be replaced by if-then-else, but what proportion of them can?
(I seem to remember hearing some figure like 70% at one point --
don't know how this was measured, though.)

     On a related point, what proportion of instances of
negation can be eliminated by using if-then-elses?  (The
problems of negation wouldn't be eliminated, of course, but if
we could replace negation by if-then-else there would be more
uniformity with other programming languages.)

--Jamie.		Original material copyright (c) 1990 by Jamie Andrews;
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