my $ref = \@list;

  for (my $i = @$ref; --$i; ) {
    my $j = int rand ($i+1);
    next if $i == $j;
    @$ref[$i,$j] = @$ref[$j,$i];
  }

  # @list is modified in place

##</code><code>##

  for (my $i = scalar(@list); --$i; ) {
    my $j = int rand ($i+1);
    next if $i == $j;
    @list[$i,$j] = @list[$j,$i];
  }