dialect.clj

;;problem 2 sum even fibonacci #s up to 4000000

(defn fib-seq []
  (let [step (fn [pair]
               [(last pair) (+ (first pair) (last pair))])]
    (map first (iterate step [0 1]))))
(def fibs (fib-seq))

(apply + (filter even? (take-while #(<= % 4000000) fibs)))