c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"sub fisher_yates_shuffle_while_loop
 {
     my $array = shift;
     my $i = @$array;
     while ( --$i )
     {
         my $j = int rand( $i+1 );
         @$array[$i,$j] = @$array[$j,$i];
     }
 }
 ;;
 my @ra = (1 .. 9);
 fisher_yates_shuffle_while_loop(\@ra);
 dd \@ra;
 @ra = (1, 2);
 fisher_yates_shuffle_while_loop(\@ra);
 dd \@ra;
 @ra = (1);
 fisher_yates_shuffle_while_loop(\@ra);
 dd \@ra;
 ;;
 ;;
 sub fisher_yates_shuffle_for_loop
 {
     my $array = shift;
     my $i = @$array;
     for ( my $i = @$array; $i; $i-- )
     {
         my $j = int rand( $i+1 );
         @$array[$i,$j] = @$array[$j,$i];
     }
 }
 ;;
 @ra = (1 .. 9);
 fisher_yates_shuffle_for_loop(\@ra);
 dd \@ra;
 @ra = (1, 2);
 fisher_yates_shuffle_for_loop(\@ra);
 dd \@ra;
 @ra = (1);
 fisher_yates_shuffle_for_loop(\@ra);
 dd \@ra;
 ;;
 ;;
 for (0 .. 9) {
   printf '%d ', int rand(3 + 1);
   }
"
[6, 3, 8, 9, 1, 7, 5, 2, 4]

[2, 1]

[1]

[9, 4, 8, 3, 1, 6, 7, 2, 5, undef]

[undef, 2, 1]

[undef, 1]

0 3 3 3 3 0 1 1 2 1