Protocols and records exist purely for polymorphism. If you want type safety, then perhaps try core.typed:

    (defalias Point
      (HMap :mandatory {:x Num, :y Num}
            :complete? true))

    (ann add-vectors [Point Point -> Point])
    (defn add-vectors [a b]
      {:x (+ (:x a) (:x b))
       :y (+ (:y a) (:y b))})