OCaml at Jane Street
Programming language researchers have long considered statically-typed functional programming languages such as OCaml, SML, and Haskell to be among the most effective programming tools available. But these languages have seen little uptake in industry outside of few niche areas such as compiler development and formal methods.
Jane Street is the exception. We decided that in a highly competitive space, there's no substitute for using the most powerful tools available. As a result, we've become perhaps the largest commercial user of OCaml, and have attracted a very strong team of functional programmers.
Outside of our own use, Jane Street is a major supporter of the functional programming community in general and the OCaml community in particular. We also write a technical blog, and release some of our software as open source.
If you want to learn more about how and why we use OCaml, here are a few sources: