effect Messages {
    fun hello() -> String;
    fun world() -> String;
}

pub fun main() ! Io -> Unit {
    try {
        print!(Messages.hello!());
        print!(", ");
        print!(Messages.world!());
        print!("\n");
    } handle Messages {
        fun hello() {
            resume "hello";
        }

        fun world() {
            resume "world";
        }
    }
}