I'd compare the two most popular web development platforms for those languages and try building similar apps in each. For haskell, that's http://www.yesodweb.c

I'd compare the two most popular web development platforms for those languages and try building similar apps in each. For haskell, that's http://www.yesodweb.com/ http://www.yesodweb.com/ and for clojure it's http://www.webnoir.org/ http://www.webnoir.org/ What trade-offs you encounter are going to be unique given what problem you are trying to solve with your web app, but the best way to see which suits you is just to take some time and try them out!