I am looking to start an experimental project using a functional language and am trying to decide beween Erlang and Haskell, and both have some points that I really like.

I like Haskell's strong type system and purity. I have a feeling it will make it easier to write really reliable code. And I think that the power of haskell will make some of what I want to do much easier.

On the minus side I get the feeling that some of the Frameworks for doing web stuff on Haskell such as Yesod are not as advanced as their Erlang counter parts.

I rather like the Erlang approach to threads and to fault tollerence. I have a feeling that the scalability of Erlang could be a major plus.

Which leeds to to my question, what has people's exerience been in implementing web application backends in both Haskell and Erlang. Are there packages for Haskell to provide some of the lightweight threads and actors that one has in Erlang?