That's a good point. I was going to use the map to build a substring array, but changed my strategy halfway through and didn't clean up. Here is a corrected version:

use strict;

my $string = shift;
my %seen;
foreach (0..(length $string) - 1) {
   my $temp = $string;
   substr $temp, $_, 1, "";
   print "$temp\n" unless $seen{$temp}++;
}
[download]

Thanks!

-Mark