pythagorean triples with for loops and explicit step

pythagorean3.ss

(import :std/iter)
(export main)

(def (main)
  (declare (fixnum) (not safe))
  (def i 1)
  (let/cc break
    (for* ((z (in-naturals 1))
           (x (in-range 1 z 1))
           (y (in-range x z 1)))
      (when (= (+ (* x x) (* y y)) (* z z))
        (displayln "(" x ", " y ", " z ")")
        (if (< i 1000)
          (set! i (1+ i))
          (break))))))