You really want to write code only once, and compile it to two targets: One for the server, one for the client. This is really hard to do in all current mainstr

You really want to write code only once, and compile it to two targets: One for the server, one for the client. This is really hard to do in all current mainstream languages. To illustrate: You have some piece of state y, and you have x = f(y) that means "x is always the value of f(y), when y changes, update x." Furthermore x is shared state across many users. On the server side you want that statement to generate code for synchronizing values of x and y across users. On the client side you want to generate code for pushing and pulling Ajax/Comet updates from the others.