;; An fn carries parameter names and no types — that is the surface syntax —
;; so it takes them from the position it is written in. An argument position
;; says what is wanted, because the callee's signature is threaded into every
;; argument; a let binding does not, and is refused saying so.
;;
;; The one thing capture did not change. It is about where the *types* come
;; from and not about what the body may see, so an fn is still written where
;; something says what it takes.
(defn main [] i32
  (let [f (fn [x] (* x 2))]
    (println (f 3)))
  0)