PHP and MongoDB

<?php
ini_set('display_errors', 1);
$document = [
  "_id" => "derickr",
  "name" => "Derick Rethans",
  "talks" => [
    [
      "title" => "Profiling PHP Applications",
      "url" => "http://derickrethans.nl/talks/profiling-phptour.pdf",
    ],
    [
      "title" => "Xdebug",
      "url" => "http://derickrethans.nl/talks/xdebug-phpbcn11.pdf",
    ]
  ]
];

$m = new MongoClient();
var_dump( $m->demo->talks->insert( $document ) );
?>

Output

Fatal error: Uncaught Error: Class "MongoClient" not found in /var/www/sites/talks.php.net/display.php(574) : eval()'d code:18 Stack trace: #0 /var/www/sites/talks.php.net/display.php(574): eval() #1 /var/www/sites/talks.php.net/objects.php(128): html->_example() #2 /var/www/sites/talks.php.net/display.php(93): _tag->display() #3 /var/www/sites/talks.php.net/objects.php(128): html->_presentation() #4 /var/www/sites/talks.php.net/show.php(122): _tag->display() #5 {main} thrown in /var/www/sites/talks.php.net/display.php(574) : eval()'d code on line 18