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clojurebinary-treezipper

Can someone give an example of how edit function for clojure.zip works?

I am a newbie to clojure and i was working with clojure.zip, and was not able to figure out how to use the edit function in it. If someone can give me a working example of how it works it would be really helpful.

say for example i have a binary tree

    45
10     57

how would i edit the value 57 and change it to say 75

Solution

  • Presuming a structure of nested vectors in which the first element is the value, the second is the left child and the third is the right child, this would work:

    (let [btree [45 [10] [57]]
      root-loc (zip/zipper vector? rest
                           (fn [[x _ _] children]
                             (vec (cons x children)))
                           btree)]
  (-> root-loc
      zip/down
      zip/right
      (zip/edit (fn [node]
                  (assoc-in node [0] 75)))
      zip/root))
;=> [45 [10] [75]]