Hi Qi, have a look at brainfuck language. Its turing complete as Python, Haskell, etc are. Then you'll learn that the quesntion "Can I do everything possible" is not at all important. You have to ask instead: Can I complete my task in reasonable time and with reasonable runtime performance etc. For most use cases Haskell is a good choice - the only real things I'm missing are - nice stack traces - completion support - because I find it relaxing not having to looking all names. This could be fixed to some extend though.. If you want to target JavaScript in browsers I'm not sure whether Haskell is the best fit either. If I were you I'd learn some Haskell - I don't think you'll regret it. By reading the mailinglists, joining the chat room ocassionally you'll learn a lot. But if you have a real task to solve - have a look whether existing solutions exist - thus "Use the best tool for the given problem". Because recoding can sometimes take longer. And eg the Java community has been much bigger in the past -> thus there are more libraries available. Eg Haskell has no htmlunit yet which interpretes JavaScript and simulates a headless browser etc. Marc Weber