gistfile1.clj

;a sample zipper
(def v2 (zip/vector-zip [[2 3] [4]]))

(defn editfn [x]
  "returns a vector with 2 numbers"
  (let [a (* x 10)]
    [(inc a) (dec a)]))

(defn inext [node-edit loc ]
  "Adds children if loc is a leaf, else returns the next node"
  (cond (zip/end? loc) loc 
        (zip/branch? loc) (zip/next loc)
        :else (let [p (-> loc (zip/edit node-edit))
                    r (-> p zip/right)]
                (if (-> r nil? not) r 
                  (let [nextnode  (-> p zip/up zip/right)]
                    (if (-> nextnode nil? not) (-> nextnode zip/next) (-> p zip/down zip/rightmost zip/next )))))))

(defn leaf-grown [editfn v]
  "edits all the leaf nodes and returns after zipping to root"
  (zip/root (first (filter zip/end? (iterate (partial inext editfn) v)))))

;the leaf nodes 2 3 and 4 have been replaced with 2 nodes each.
(is (= [[[21 19] [31 29]] [[41 39]]] (leaf-grown editfn v2)))  

;the leaf nodes alone
(is (= '(21 19 31 29 41 39) (map zip/node (leafnodes (-> (leaf-grown editfn v2) zip/vector-zip)))))