Simple no-loop failure? example

; Creates a 800x600 field and (is intended) to draw a new 10x10 rectangle after each mouse click
; Nevertheless..
(ns sample.core
  (:use quil.core))

(def cell-size 10)
(def w (* 80 cell-size))
(def h (* 60 cell-size))

(def X (atom 0))
(def Y (atom 0))

(defn draw []
  (do
    (stroke-weight 1)
    (stroke 0)
    (fill 255)
    (swap! X + cell-size)
    (swap! Y + cell-size)
    (rect @X @Y cell-size cell-size)))

(defn mouse-handler []  ; We never see this happen
      (redraw) ; This block isn't call at all: After mouse click we neither see the redraw happen
      (println "abacaba") ; Nor any output.
)

(defn setup []
  (background 40)
  (no-loop)) ; https://github.com/quil/quil/wiki/no~loop

(defn field []
  (sketch
    :title "sample"
    :draw draw
    :setup setup
    :mouse-pressed mouse-handler ; None of 3 types of possible handlers gives the correct result
    :size [w h]))

(field)