Dan Miller, a core platform engineer at Etsy, has a new post on his personal site sharing his results from a comparison of the variable typing systems between the Hack language (created by Facebook) and what's coming in PHP7.

One of the exciting things about PHP 7, aside from the incredible performance improvements, is the introduction of scalar type hintingHack. I wanted to find out if you could execute the same code in PHP 7 and Hack, and what the differences in execution might be. Here's what I found out.

He starts by describing his setup (the versions of PHP7 and HHVM he's using) and shares a few simple examples. He uses the same(ish) code in both and points out some of the differences in what happens when each is executed. He also points out some of the differences in the features between the two (such as Hack not allowing for default arguments with a value of null). He tries a few more complicated things too, like mixing strict and non-strict files, and the findings. He ends the post with some of his overall thoughts of his results and his excitement about what the future holds for PHP7 and the hinting it will provide.