use strict;
use warnings;
use Tk;

my $mw = MainWindow->new (-title => 'Hello World');

my @arr=('first', 'second', 'third');
my %hash = (A => 100, B => 200, C => [@arr], D => \&hi, E => $mw);

$hash{'A'}=100;
$hash{'B'}=200;
$hash{'C'}=[@arr];

for (sort keys %hash) {
    print "$_ => ";

    if (ref($hash{$_}) eq 'ARRAY') {
        print "Array: ", join(', ', @{ $hash{$_} });
    }
    elsif (ref($hash{$_}) eq 'HASH') {
        # do something else
        print "Hash: ...";
    }
    else {
        print "Scalar: $hash{$_}";
    }

    print "\n";
}

sub hi {
    print "hello World";
}

##</code><code>##

A => Scalar: 100
B => Scalar: 200
C => Array: first, second, third
D => Scalar: CODE(0x21bdf50)
E => Scalar: MainWindow=HASH(0x21d97ac)

##</code><code>##

    elsif (ref($hash{$_})) {
        print "Unknown ref: $hash{$_}";

##</code><code>##

A => Scalar: 100
B => Scalar: 200
C => Array: first, second, third
D => Unknown ref: CODE(0x21be538)
E => Unknown ref: MainWindow=HASH(0x21d9e38)