jclaggett

(defmacro lazy
  "Returns a lazy sequence of calls to (f). Arguments are evaluated once as needed.
   (lazy f a b c d) --> (a, (f a b), (f (f a b) c), (f (f (f a b) c) d))"
  ([f x]
    `(lazy-seq
      (list ~x)) )
  ([f x form & more]
    `(lazy-seq
      (let [x# ~x]
        (cons x#