Companies often get a lot of hate for buying open-source and taking it closed.

We should really celebrate Facebook for doing the opposite here!

"Based on the success of these research advances, we formed a startup company, Monoidics, in 2009. Monoidics joined Facebook in 2013, and since then we have adopted the continuous development and deployment style practiced at Facebook and improved our analyzer based on an iterative feedback loop between our analyzer's development team and Facebook's mobile software engineers. We have demonstrated that verification technology can indeed thrive when applied to codebases at Facebook's scale and pace of change."