Haskell vs PHP: simple domain logic example

pcb.hs

newtype Rule = Rule String deriving (Show)

class RuleSet a where
  getRules :: a -> [Rule]

data Bus = Bus [Rule] deriving (Show)
instance RuleSet Bus where
  getRules (Bus rules) = rules

data Net = Net Bus [Rule] deriving (Show)
instance RuleSet Net where
  getRules (Net bus rules) = getRules(bus) ++ rules


bus = Bus [Rule "Rule 1", Rule "Rule 2"]
net = Net bus [Rule "Own net rule"]
main = putStrLn(show $ getRules(net))  

pcb.php

<?php

class Rule {
    private $text;

    function __construct($text) {
        $this->text = $text;
    }
}

interface RuleSet {
    function getRules();
}

class Bus implements RuleSet {
    private $rules;

    function __construct(array $rules) {
        $this->rules = $rules;
    }

    function getRules() {
        return $this->rules;
    }
}

class Net implements RuleSet {
    private $ownRules;
    private $bus;

    function __construct(Bus $bus, array $ownRules) {
        $this->bus = $bus;
        $this->ownRules = $ownRules;
    }

    function getRules() {
        return array_merge($this->bus->getRules(), $this->ownRules);
    }
}

$bus = new Bus([new Rule("Rule 1"), new Rule("Rule 2")]);
$net = new Net($bus, [new Rule("Own rule")]);
var_dump($net->getRules());