data.clj

(ns ring.util.data
  "Miscellaneous functions for manipulating data structures.")

(defn assoc+
  "Associate a key with a value in a map. If the key already exists in the map,
  a vector of values is associated with the key."
  [map key val]
  (assoc map key
    (if-let [cur (get map key)]
      (if (vector? cur)
        (conj cur val)
        [cur val])
      val)))