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From: bourguet@my-deja.com
Subject: Re: Eight Queens problem (was Re: Kindness)
Date: 1999/09/08
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Date: 1999-09-08T00:00:00+00:00
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In article <7r4edb$gg2$1@nnrp1.deja.com>,
  Robert Dewar <robert_dewar@my-deja.com> wrote:
> In article <7r2fc6$1sc$1@nnrp1.deja.com>,
>   bourguet@my-deja.com wrote:
> > Do you want to say it is the canonical example of use or it is
> an as
> > good example: there is another way to solve the problem which
> usually
> > come first to mind?
>
> Nothing so complicated, just that, as factorial is typically
> used in a text book to illustrate recursion, 8Q is used to
> illustrate backtracking.
>
> I agree that simple tail recursion is a horrible example for
> motivating recursion.

Is the classical way of writing the factorial

function fact(n : natural) return natural is
begin
   if n = 0 then
      return 1;
   else
      return n*fact(n-1);
   end if;
end fact;

tail recursive? There is a multiplication to be executed after the
return. Writing a tail recursive version is a little more complicated
and is an interesting thing to do. But obviously you are then even
nearer of the iterated version.

> Here is the example I always use, with a little driver:
[recursive version of print_int]
Indeed this is more interesting than factorial for introducing
recursion.

-- Jean-Marc


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