use 5.026;
use warnings;

use Data::Dumper;

my $numX = 5;
my $numY = 7;

my $key = q{a};
my %posns =
   map {
           my $y = $_;
           map {
                   my $x = $_;
                   $key ++ => [ $x, $y ]
               } 0 .. $numX - 1 ;
       } 0 .. $numY - 1;

my $rcKeySorter = sub {
   my $rhPosns = shift;
   my @sortOrder =
      map { unpack q{x4a*}, $_ }
      sort
      map { pack q{Na*}, length, $_ }
      keys %{ $rhPosns };
   return \ @sortOrder;
   };

print Data::Dumper
   ->new( [ \ %posns ], [ qw{ *posns } ] )
   ->Sortkeys( $rcKeySorter )
   ->Dumpxs();

##</code><code>##

%posns = (
           'a' => [
                    0,
                    0
                  ],
           'b' => [
                    1,
                    0
                  ],
           'c' => [
                    2,
                    0
                  ],
           'd' => [
                    3,
                    0
                  ],
           'e' => [
                    4,
                    0
                  ],
           'f' => [
                    0,
                    1
                  ],
           'g' => [
                    1,
                    1
                  ],
           'h' => [
                    2,
                    1
                  ],
           'i' => [
                    3,
                    1
                  ],
           'j' => [
                    4,
                    1
                  ],
           'k' => [
                    0,
                    2
                  ],
           'l' => [
                    1,
                    2
                  ],
           'm' => [
                    2,
                    2
                  ],
           'n' => [
                    3,
                    2
                  ],
           'o' => [
                    4,
                    2
                  ],
           'p' => [
                    0,
                    3
                  ],
           'q' => [
                    1,
                    3
                  ],
           'r' => [
                    2,
                    3
                  ],
           's' => [
                    3,
                    3
                  ],
           't' => [
                    4,
                    3
                  ],
           'u' => [
                    0,
                    4
                  ],
           'v' => [
                    1,
                    4
                  ],
           'w' => [
                    2,
                    4
                  ],
           'x' => [
                    3,
                    4
                  ],
           'y' => [
                    4,
                    4
                  ],
           'z' => [
                    0,
                    5
                  ],
           'aa' => [
                     1,
                     5
                   ],
           'ab' => [
                     2,
                     5
                   ],
           'ac' => [
                     3,
                     5
                   ],
           'ad' => [
                     4,
                     5
                   ],
           'ae' => [
                     0,
                     6
                   ],
           'af' => [
                     1,
                     6
                   ],
           'ag' => [
                     2,
                     6
                   ],
           'ah' => [
                     3,
                     6
                   ],
           'ai' => [
                     4,
                     6
                   ]
         );