There's Cloud Haskell which is an attempt to do Erlang style distributed concurrency in Haskell. For non-distributed concurrency, you can already get away with

There's Cloud Haskell which is an attempt to do Erlang style distributed concurrency in Haskell. For non-distributed concurrency, you can already get away with using Haskell's green threads and channels. Furthermore, there's the beginning of a hot code swapping system in GHC now, but it's not terrifically popular at the moment---it was built for a particular use at Facebook and hasn't gotten too far from there. It's worth talking about why Cloud Haskell is tough, though. The primary issue is that Haskell doesn't have any kind of transparency into functions---if you are given a type of `(a -> b)` there's no way to examine what it is on the inside, no concept of source that could be sent to another node. This limits the kinds of messages and spawning that can happen in a distributed Haskell system. The Cloud Haskell project is working to remove as much of this limitation as possible, though.