; Iter it.2 positive (DD-4 / D2): a fn whose body contains a
; `(loop …)` must declare `!Diverge`. This one does — its effect row
; carries `Diverge` (and `IO`, since it `print`s the result), so the
; existing declared-vs-raised reconciliation accepts it. Modelled on
; `loop_counter.ail` (it.1) with `Diverge` added to the effect row.

(module loop_needs_diverge

  (fn main
    (doc "Sum 1..10 via an accumulator loop; loop-bearing ⇒ !Diverge. Expected stdout: 55.")
    (type (fn-type (params) (ret (con Unit)) (effects IO Diverge)))
    (params)
    (body
      (app print
        (loop ((var acc (con Int) 0) (var i (con Int) 1))
          (if (app > i 10)
            acc
            (recur (app + acc i) (app + i 1))))))))