At first I thought of Haskell as a not practical applicable, but very interesting language. But Yesod is an excellent Framework completely written in Haskell. Studying it, I got convinced, that Haskell is made for Web-Development. Btw. Michael Snoyman does great effort to spread Haskell and he is worth to be supported. He also wrote Yesod and is one of the authors of the FP Complete - Website.
Must read! (But I agree, that you should be familiar with Haskell)