(defstruct range 
  (max (* -1 most-positive-fixnum))
  (min most-positive-fixnum)
  (ready? t))

(defstruct (dist (:include range))
  all
  (key   #'first)
  (value #'rest)
  (sum 0) 
)

(defstruct (gaussian (:include range))
  (sumsq 0)
  (sum 0)
  (n 0)
  mean
  stdev)