Clojure Lens Implementation

lens.clj

(defn lens [getter setter]
  (fn [fmap vf in]
    (fmap (partial setter in)
          (vf (getter in)))))

(defn lupdate [lens f in]
  (lens (fn [f a] (f a))
       f
       in))

(defn lset [lens in v]
  (lupdate lens in (constantly v)))

(defn lget [lens in]
  (lens (fn [_ a] a)
        identity
        in))

(deftype Person [name salary address])
(deftype Address [street zip])

(def lname (lens #(.name %) (fn [p n] (Person. n (.salary p) (.address p)))))

Haskell uses the Functor type to select fmap implementation. Why not pass in fmap directly?

Because you explicitely pass fmap I prefer your impl to @ctford's one.
I think line 12 should be (lupdate lens (constantly v) in))