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clojurerecords

Return plain map from a Clojure record

I have a record:

(defrecord Point [x y])
(def p (Point. 1 2))

Now I want to extract just the map from the record. These ways get the job done. Are these good ways? Are there better ways?

(into {} (concat p))
(into {} (map identity p))
(apply hash-map (apply concat p))

I was hoping there might be a cleaner way, perhaps built-in to the notion of a record.

Solution

  • Records are maps

    (defrecord Thing [a b])

(def t1 (Thing. 1 2))
(instance? clojure.lang.IPersistentMap t1) ;=> true

    So, in general there is no need to coerce them into a APersistentMap type. But, if desired you do so with into:

    (into {} t1) ;=> {:a 1, :b 2}

    If you want to traverse an arbitrary data structure, including nested records, making this transformation, then use walk

    (def t2 (Thing. 3 4))
(def t3 (Thing. t1 t2))
(def coll (list t1 [t2 {:foo t3}]))

(clojure.walk/postwalk #(if (record? %) (into {} %) %) coll)
;=> ({:a 1, :b 2} [{:a 3, :b 4} {:foo {:a {:a 1, :b 2}, :b {:a 3, :b 4}}}])