Eta
The Eta Programming Language, a dialect of Haskell on the JVM
...This allows you to harness the best of both ecosystems to build your applications quickly and effectively. Eta's concurrency support helps you to build highly scalable systems. Eta has a strongly-typed Foreign Function Interface (FFI) that allows you to safely interoperate with Java. Eta has global type inference, giving you a dynamic language experience, but with a strong typing hidden underneath. Eta offers a wide range of strategies for handling concurrency including Software Transaction Memory (STM), MVars, and Fibers. Using the powerful and type-safe Servant web framework, we define our API as a type and the handler types for each endpoint are automatically generated and conversions happen automatically.