use strict;
use warnings;

use feature qw{ say };

#       ===========
package Incrementor;
#       ===========

use Tie::Scalar;
our @ISA = qw{ Tie::StdScalar };

sub TIESCALAR
{
    my( $pkg, $value ) = @_;
    $value //= 0;
    return bless \ $value, $pkg
}

sub FETCH
{
    my $self = shift;
    return ${ $self } ++;
}

package Main;

my @arr = qw{ a b c d e };

tie my $inc, q{Incrementor};
say join $inc, @arr;

say q{-} x 20;
say join $inc, @arr;

##</code><code>##

a1b2c3d4e
--------------------
a6b7c8d9e

##</code><code>##

a0b0c0d0e
--------------------
a1b1c1d1e