tree-seq

function

since v0.0-927

clojure.core/tree-seq

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Details:

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Source docstring:

Returns a lazy sequence of the nodes in a tree, via a depth-first walk.
branch? must be a fn of one arg that returns true if passed a node
that can have children (but may not).  children must be a fn of one
arg that returns a sequence of the children. Will only be called on
nodes for which branch? returns true. Root is the root node of the
tree.

(defn tree-seq
  [branch? children root]
   (let [walk (fn walk [node]
                (lazy-seq
                 (cons node
                  (when (branch? node)
                    (mapcat walk (children node))))))]
     (walk root)))

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