Factorial in Perl

Example for versions perl 5.8.8

This example uses the reduce function from the List::Util module. Note that we have to put an extra 1 in the beginning, so that it will work when 1 .. $n is empty (i.e. when $n is 0). 

use List::Util qw(reduce);
sub fact {
  my $n = shift;
  reduce { $a * $b } 1, 1 .. $n
}

foreach my $i (0..16) {
    print "$i! = ", fact($i), "\n";
}