fun main () =
s1 <- source "";
s2 <- source "";
let
fun echo s = return s
fun echoer () =
v1 <- get s1;
v1' <- rpc (echo v1);
set s2 v1'
in
return <xml><body>
<dyn signal={v <- signal s2; return (cdata v)}/><hr/>
<ctextbox source={s1}/> <button onclick={echoer ()}/>
</body></xml>
end