Facebook has a very large PHP code base. At this scale, a dynamic language leads to a challenging situation in terms of tooling. The lack of static knowledge can make simple tasks very time consuming. Something as simple as renaming a method can cause unexpected problems because not all the code paths were captured through testing. In the past few years, Facebook spent time working on pragmatic approaches to improve the tooling around PHP. More recently, we started applying static-analysis and type-inference techniques to PHP. In this talk I will present how we applied these techniques to PHP and how we scaled them for Facebook. Since most of the tools were written in OCaml, they constitute a good example of an industrial scale application using a functional programming language.
Julien is a member of the HipHop team. HipHop is a JIT compiler for PHP used at Facebook. Most of my work is focused on static analysis (front-ent work).
Slides are here: http://cufp.org/2013/slides/verlaguet.pdf