• Pure functions get faster when you memoize them.

• A memoized function caches its return values

• If you call it with the same arguments, it returns the cached value

         { my @fact = (1);
             sub factorial {
             my $n = shift;

             return $fact[$n] 
               if defined $fact[$n];

             $fact[$n] = 
               ($n == 0 ? 1 
                        : $n * factorial($n-1));
           }
         }

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Copyright © 1998 M-J. Dominus