What happened when you ran your code? What happens when you run this simplified version:

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"sub shuffle {
   my $array = shift;
   my $i;
   for ($i = @$array; --$i; ) {
     my $j = int rand ($i+1);
     next if $i == $j;
     @$array[$i,$j] = @$array[$j,$i];
     }
   }
 ;;
 my @lines = qw(foo bar baz quux);
 my @reordered = shuffle(\@lines);
 dd \@reordered;
"
[0]
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Why does the  @reordered array always end up with a single element of 0? (Update: What do you get if you dump  @lines after shuffling, and why?)