multiple-value-bind.clj

(def *multi-value* false)

(defmacro with-values [vars expr body]
  `(binding [*multi-value* true]
     (let [[~@vars] ~expr]
       ~body)))

(defn values [& vals]
  (if *multi-value*
    vals
    (first vals)))

(values 1 2 3)
;;=> 1
(values)
;;=> nil
(with-values [a b c]
  (values 1 2 3 4 5) [a b c])
;;=> [1 2 3]