converge.clj

(defn -sqr [a b] (let [d (- a b)] (* d d)))

(defn -dist [a b] (Math/sqrt (-sqr a b)))

(defn converge
  ([epsilon coll] (converge epsilon -dist coll))
  ([epsilon distance coll]
  (ffirst 
    (drop-while 
      (fn [[a b] & more] (< epsilon (distance a b)))
      (partition 2 1 coll)))))