$monk1 = 'Jack';
$monk2 = 'John';
$monk3 = 'Mark';
$monk4 = 'Rudolf';

#order of monks important - using array - square brackets
$bank_left1 = [$monk1, '', $monk2];
$bank_left2 = [];
$bank_left3 = [];
$bank_left4 = [];
# order of banks important - use array
$left_nave = [$bank_left1, $bank_left2, $bank_left3, $bank_left4];

$bank_right1 = [];
$bank_right2 = [$monk3];
$bank_right3 = [];
$bank_right4 = [];
$right_nave = [$bank_right1, $bank_right2, $bank_right3, $bank_right4];

# existence of elements is important, order not - lets do hash
$church = {'left nave'=>$left_nave, 'right nave'=>$right_nave, 'altar'=>1, 'tabernacle'=>1};

# lets declare hash of arrays at once, order of plants not important, but array is here more convenient.
# See, instead of (key, value) pairs I use (key, reference-to-array).
$garden = {'plants'=>['potato', 'carrot', 'apple tree'], 'monks'=>[$monk4], 'rain'=>1};

# and finally whole monastery, not rich, but its our home :)
$monastery = {'church'=>$church, 'garden'=>$garden};

# see how it looks and where monks reside:
use Data::Dumper;
print Dumper $monastery;