(defprotocol T
  (t [this] "Gives the transformation to calculus stuff")
  (free [this] "Gives the free variables in the term")
  (r [this] "Gives the transformation to easy-read"))

(defrecord lterm [var body]
  T (t [this]
       (println (type body))
       (println (instance? user.lterm body))
       (if  (instance? lterm body)  (println "int "))))

(t (lterm. :x (lterm. :y :z)))