;;;; The session's fixture for generics in the dev loop.
;;;;
;;;; A generic [defn] never reaches [Tast.fns] — only its copies do — so every
;;;; question the editor asks about one has to be answered by expanding the
;;;; name. This file is the smallest program that makes each of those
;;;; questions concrete: one generic used at two element types, one generic
;;;; that calls another so that instantiation has to be transitive, and one
;;;; call site whose element type is *not* used anywhere else, so that a
;;;; redefinition can reach a copy the process was never built with.

(defvar counter i64)

(defn put-at [xs [$t] i i32 v $t] ()
  (set (at xs i) v))

;;; Calls [put-at] at its own variable, so the copy of [put-at] is generated when
;;; [hold] is instantiated and not before.
(defn hold [xs [$t] v $t] ()
  (put-at xs 0 v))

(defn pick [xs [$t]] $t
  {:where (ordered? $t)}
  (let [m (at xs 0)]
    (dotimes [i (len xs)]
      (set m (min m (at xs i))))
    m))

(defn step [] ()
  (let [ns [5 3 9 1]
        fs [2.5 0.5 1.5]]
    (hold (slice ns 0 4) 7)
    (hold (slice fs 0 3) 0.25)
    (set counter (+ counter (i64 (pick (slice ns 0 4)))))))

(defn main [] ()
  (step)
  (println counter))