On the Slack Engineering blog there's a new post from one of their engineers talking about a choice the company made about their platform - they decided to take PHP seriously. In this post author Keith Adams talks about why they chose PHP and what kind of experiences they've had with it in their own environment.

Slack uses PHP for most of its server-side application logic, which is an unusual choice these days. Why did we choose to build a new project in this language? Should you?

PHP-the-language has many flaws, which undoubtedly have slowed these efforts down, but PHP-the-environment has virtues which more than compensate for those flaws. And the options for improving on PHP’s language-level flaws are pretty impressive. On the balance, PHP provides better support for building, changing, and operating a successful project than competing environments. I would start a new project in PHP today, with a reservation or two, but zero apologies.

He starts with some background on the history of PHP itself, where the language came from and what kinds of issues it tries to mainly solve. He then gets into some of what he sees are the "virtues of PHP" including the blank slate at the start of every request, one-request-one-process concurrency and the fast programmer workflow. He then gets into the "bad stuff" they've found when working with PHP, things like surprise type conversions, a "failure-oblivious philosophy" and inconsistencies in the standard library. Finally he looks into two options (created by Facebook to improve its use of PHP) - HHVM and the Hack language - and how it was integrated into their environment.