#!/ActivePerl/bin/perl

use strict;
use warnings;
use feature (qw/state say/);

store_and_print_hash('a');
store_and_print_hash('b');
store_and_print_hash('c');

store_and_print_array('x');
store_and_print_array('y');
store_and_print_array('z');

sub store_and_print_hash {
   state %hash;
   my $key = shift;
   $hash{$key} = 1;
   say "Hash keys: (" , join(', ' , sort keys %hash), ")";
}

sub store_and_print_array {
   state @array;
   my $value = shift;
   push @array, $value;
   say "Array values: (" , join(', ' , @array), ")";
}
[download]

Hash keys: (a)
Hash keys: (a, b)
Hash keys: (a, b, c)
Array values: (x)
Array values: (x, y)
Array values: (x, y, z)
[download]