gistfile1.clj

(macroexpand '(fn 
                ([x] x)
                ([x & xs] (cons x xs))))
=> 
(clojure.core/with-meta
  (cljc.core/reify
    clojure.lang.Fn
    clojure.lang.IFn
    (invoke [G__4128 G__4129] (let [[x] [G__4129]] x))
    (invoke
      [G__4130 G__4131 G__4132]
      (let [[x] [G__4131] [& xs] G__4132] (cons x xs))))
  {:tag nil})

((fn 
    ([x] x)
    ([x & xs] (cons x xs))) 1 [2 3])
=> (1 2 3)

((fn 
    ([x] x)
    ([x & xs] (cons x xs)))  :hello)
=> :hello