(def a (rationalize 1.0e50))
(def b (rationalize -1.0e50))
(def c (rationalize 17.0e00))

(+ (+ a b) c)
;=> 17

(+ a (+ b c))
;=> 17

(let [a (rationalize 0.1)
      b (rationalize 0.2)
      c (rationalize 0.3)]
  (=
    (* a (+ b c))
    (+ (* a b) (* a c))))
;=> true