An immutable trie idea

immutable_trie.cljc

(ns alexandergunnarson.immutable-trie)

(defrecord TrieNode
  [val complete? a b c d e f g h i j k l m n o p q r s t u v w x y z])

(defn node
  ([val] (node val false))
  ([val complete?]
    (TrieNode. val complete?
      nil nil nil nil nil
      nil nil nil nil nil
      nil nil nil nil nil
      nil nil nil nil nil
      nil nil nil nil nil nil)))

; ti:me
; --:cket
(assoc (node \t)
  :i (assoc (node \i)
       :m (assoc (node \m)
            :e (node \e true))
       :c (assoc (node \m)
            :k (assoc (node \k)
                 :e (assoc (node \e)
                      :t (node \t true))))))

; We could have represented the Trie using arrays,
; but not if we wanted to have the Trie behave immutably and
; be postwalkable etc., then it's not a good idea