clojure - Why does y = 0 when I run println? -

how come when run

  (def y 0)   (doseq [x (range 1000)] (if (or (= (mod x 3) 0) (= (mod x 5) 0)) (+ y x)))   (println y) 

it prints 0 if no addition has taken place but

(doseq [x (range 1000)] (if (or (= (mod x 3) 0) (= (mod x 5) 0)) (println x))) 

will print out of corresponding numbers match conditions?

in clojure, values immutable. y is, , 0 of eternity. (+ y 1) 1, , 1. (+ y 1) not change value of y, evalutates result of adding 1 immutable value y.

try this:

(println    (reduce      (fn [y x]       (if (or (= (mod x 3) 0)                (= (mod x 5) 0))          (+ y x) y))   0 (range 1000))) 

here, build y on time reducing on range in question. if match condition, add next value (x). if don't match condition, return y.

look reduce function.

note: there typos, wrote on phone