You can use variables in Haskell as well, no problem. It just forces you to stack your monad on IO, STM or some other mutable-value-supporting monad, of which t

You can use variables in Haskell as well, no problem. It just forces you to stack your monad on IO, STM or some other mutable-value-supporting monad, of which there are several. The only difference worth mentioning is that they type system won't allow "leaks".