pythagorean triples with hand-written loops

pythagorean2.ss

(import :std/iter)
(export main)

(def (main)
  (declare (fixnum) (not safe))
  (def i 1)
  (let/cc break
    (let lpz ((z 1))
      (let lpx ((x 1))
        (if (< x z)
          (let lpy ((y x))
            (if (< y z)
              (begin
                (when (= (+ (* x x) (* y y)) (* z z))
                  (displayln "(" x ", " y ", " z ")")
                  (if (< i 1000)
                    (set! i (1+ i))
                    (break)))
                (lpy (1+ y)))
              (lpx (1+ x))))
          (lpz (1+ z)))))))