As the author says, there's quite a lot of imperative stuff in this design. I'm still on the fence about whether that's the best way to build large applications with GUIs, network access, etc.<p>With the imperative approach, you make liberal use of the IO monad. There's a lot of explicit reading from and writing to mutable storage. If you're doing this approach right, you mostly just use the IO monad for actual IO and threading; most of the real logic of the program is kept pure. This approach has the advantage of being familiar. And more importantly, it just plain works. It's how I tend to do things.<p>Yet I can't help but wonder if there's a better way. The above approach, while comfortable, leaves me with a bad taste in my mouth, like I'm somehow fighting against the language. I've often heard functional reactive programming (FRP) described as the best alternative. Though I remain skeptical. I'd be interested in opinions about the future of FRP.