Feature suggestion -- return if true

[Jussi Piitulainen]

Gregory Ewing writes:
> Chris Angelico wrote:
> 
> > Question: How many factorial functions are implemented because a
> > program needs to know what n! is, and how many are implemented to
> > demonstrate recursion (or to demonstrate the difference between
> > iteration and recursion)? :)

(I can't get to the parent directly, so I follow up indirectly.)

Factorials become an interesting demonstration of recursion when done
well. There's a paper by Richard J. Fateman, citing Peter Luschny:

<http://www.cs.berkeley.edu/~fateman/papers/factorial.pdf>
<http://www.luschny.de/math/factorial/FastFactorialFunctions.htm>

Fateman's "major conclusion is that you should probably not use the
'naive' factorial programs for much of anything". I take this to
include their use as examples of recursion, unless the purpose is to
make the idea of recursion look bad.