tag expansion

tag-expand.clj

(defn expand-tags
  "Expands set of tags using mapping of sets of base tags to
   other (single) tags, example:

     {#{:tomatoes :potatoes :legumes} :culinary-vegetables
      #{:peanuts :lentils} :legumes
      #{:tomatoes :legumes} :botanical-fruits}"
  [tags expansions]
  (let [matches (filter (fn [[base-set _]] (some base-set tags)) expansions)
        new-tags (mapcat to-coll (map val matches))
        expanded (set (concat tags new-tags))]
    (if (= tags expanded)
      tags
      (recur expanded expansions))))