Biilmann here, I&#x27;m definitively not at Facebook no :)<p>I&#x27;ve run Haskell services in production for more than 4 years and still operate 4 of them to this date. I also contributed the wai-eventsource module to the Yesod project and build a Haskell powered eventsource addon for Heroku.<p>It&#x27;s not my impression that there are tons of other people in the bay area with as much experience in actually using Haskell for real world production stuff. Most of them are probably at Facebook now and the journalist behind the article did interview them...<p>That said, it&#x27;s absolutely true that for Netlify I now use Go for the tasks I would have used Haskell for earlier.<p>Haskell is an awesome, mindblowing language, and when I started using it for production tasks it was by far the best tool for the job at the time. By now, however, Go is a far more pragmatic choice for most of the tasks I used Haskell for before.<p>Unless your whole stack is Haskell based, the context switching involved in going back and forth between more traditional languages and Haskell are really brutal. Apart from that, it&#x27;s very easy to bring someone new onto a team and teach them enough Go to be productive in a day or two. You just can&#x27;t do that with Haskell.<p>That said, it looks like a really, really good fit for what they&#x27;re doing at Facebook with regards to spam filtering. I can totally see how you can make a safe DSL for rules that will be statically type checked and handle concurrency without any need for developers to think about it, and the Haskell runtime is incredible for these kind of things.