[latkin]

They are also known to have used F#, and even provided a testimonial to this effect: http://fsharp.org/testimonials/. Can't say if it's still used, though. That's two recent high-profile acquisitions (with Jet.com) for F# shops.

> At Kaggle we initially chose F# for our core data analysis algorithms because of its expressiveness. We’ve been so happy with the choice that we’ve found ourselves moving more and more of our application out of C# and into F#. The F# code is consistently shorter, easier to read, easier to refactor, and, because of the strong typing, contains far fewer bugs.

> As our data analysis tools have developed, we’ve seen domain-specific constructs emerge very naturally; as our codebase gets larger, we become more productive.

> The fact that F# targets the CLR was also critical - even though we have a large existing code base in C#, getting started with F# was an easy decision because we knew we could use new modules right away.