That way lies SOAP, and it's not the compiler that tells the client it can't call an API some way but a broader build tool. And you still need some runtime veri

That way lies SOAP, and it's not the compiler that tells the client it can't call an API some way but a broader build tool. And you still need some runtime verification somewhere on the server anyway since without it nothing stops any arbitrary stream of bytes. My own related exaggeration is that type declarations without performance gains are useless. Get them out of my dynamic langs unless you can deliver the performance goods. (Like Common Lisp can. It can also tell you you're stupid locally trying to make an invalid call, at compile time, since COMPILE is built-in.)