We're a startup in London (shameless plug: www.nstack.com) using Haskell to develop a containerised microservices platform, bringing in lots of low-level Linux coding along with high-level concepts such as typed DSLs.

So far it's working extremely well for us and has been a great decision - letting us build complex/reliable systems really quickly and effectively. It is also very good for attracting amazing people, and we have found a small Haskell team can deliver truly spectacular product. This does on how you architect a Haskell codebase: e.g. you could spend a ton of time focusing on the most pure approach vs. pragmatism, so it's a balancing act.