- array_merge: documentation ( source)
- var_export: documentation ( source)
<?php
echo var_export(array('type' => 'object', 'properties' => array('one' => 'one')) + array('properties' => array('two' => 'two')));
echo var_export(array_merge(array('type' => 'object', 'properties' => array('one' => 'one')), array('properties' => array('two' => 'two'))));