This has caught a lot of people's imagination! Here's my offering. It's a shame the original array is called 'original_array', otherwise it could have been a lot shorter!

  my @original_array = qw/ 5 100 2 8 40 /;
  my @sequence;
  
  @sequence[
    sort {
        $original_array[$a] <=> $original_array[$b]
    }(0 .. $#original_array)
  ] = 'A' .. 'Z';

  print "@sequence\n";
[download]

output

  B E A C D
[download]

Rob