Yesod
A RESTful Haskell web framework built on WAI
...It leverages Haskell's strong static typing, compile-time safety checks, Template Haskell, and domain-specific quasiquoters to ensure high reliability and performance. Safety & security guaranteed at compile time. Developer productivity: tools for all your basic web development needs. Raw performance, fast, compiled code. Techniques for constant-space memory consumption. Asynchronous IO, this is built in to the Haskell programming language (like Erlang).