Core points
Facebook began developing HipHop for PHP in 2008. Their goal is to speed up PHP execution, and the first version of the project consists of HPHPc/HPHPi. HPHPc is a PHP to C converter for deploying code to production servers, while HPHPi is an interpreter used during the development and debugging phases.
HPc does a great job in improving performance, but it's not without problems: keeping HPHPc and HPHPi synchronized is very cumbersome, and there are still some differences between the converted code and the explained code. That's why Facebook decided in 2010 to take another approach and created HHVM, a new virtual machine designed to replace the Zend engine used by PHP. By the end of 2012, HHVM's performance was comparable to previous HPHPc and quickly surpassed it.
HHVM is designed to achieve compatibility and optimal performance with Zend engine functions simultaneously. Facebook claims that after switching from PHP APC to HHVM, the speed has been increased by 3 to 10 times and the memory usage has been reduced by half. Of course, it really depends on the application (the 10x increase is the code base for Facebook). This article will not focus on compatibility or performance, as there are already a large number of resources available, you can check out the HHVM blog or search for "hhvm benchmark". To learn more about HipHop and HHVM, read the previous SitePoint article.
Instead, this article will focus on Hack, an improved version of the PHP language designed to improve security, performance, and development efficiency. Please note that HHVM supports both Hack and PHP. Although Hack has been used on all Facebook’s production servers, there is currently little information leaked. In short, Hack is Facebook's PHP6 - it is designed to fix most of the current PHP issues while adding some new features such as static typing.
Not all tools and documents have been published at this time. However, the latest HHVM source code already supports Hack. You can install the Vagrant virtual machine to start experimenting with Hack and run the code snippet in this article:
# 确保你的机器上已安装Vagrant $ git clone https://github.com/vicb/hhvm-vagrant.git $ cd hhvm-vagrant $ vagrant up
Now you can write your first Hack program:
<?hh require "/vagrant/www/xhp/php-lib/init.php"; $hello = "Hello HACK!"; echo <html><title>{$hello}!</title><h1>{$hello}</h1></body></html>;
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