cx.clj

(defmacro cx [& classes]
  "This macro compiles this:
    (cx :one true :two true :three false :four (pos? 1))

   Into this:

     [ \"one two\", 1 > 0 ? \"four\" : null ].join(\" \")
  "
  (let [class-map#   (partition 2 classes)
        groups#      (group-by (fn [[k v]]
                                 (cond
                                   (= v 'true)  true
                                   (= v 'false) false
                                   :else        nil))
                       class-map#)
        true-class#  (get groups# true)
        check-class# (get groups# nil)]
    `(.join (cljs.core/array 
              ~(str/join " " (map #(name (first %)) true-class#))
              ~@(for [[class# test#] check-class#]
                  `(when ~test# ~(name class#))))
       " ")))