(module loop_sum_to
  (fn sum_to
    (type (fn-type (params (own (con Int))) (ret (own (con Int)))))
    (params n)
    (body
      (loop (acc (con Int) 0) (i (con Int) 1)
        (if (app gt i n)
            acc
            (recur (app + acc i) (app + i 1)))))))