For one, GHC gives you M:N threads with the runtime handling the async IO under the hood, making it possible to write code in a simple blocking style while stil

For one, GHC gives you M:N threads with the runtime handling the async IO under the hood, making it possible to write code in a simple blocking style while still getting use of all your cores and having fast IO. This is also true for Erlang, Go, and a few others, though, and it's not terribly relevant for lots of simple web code, but it is a practical advantage.