I wouldn't say it's an alternative any more than Haskell is an alternative to Java. It's a different language and ecosystem. That said, F# is pretty nice. It's

I wouldn't say it's an alternative any more than Haskell is an alternative to Java. It's a different language and ecosystem. That said, F# is pretty nice. It's opt-in laziness for .NET compatibility but laziness is pervasive. There's no forced purity though. On the plus side it's easy to interact with anything that has .NET bindings.