;;;; A program whose callers go stale, for the signature word a dev cell
;;;; carries (docs/BUILT.md, "A signature change installs").
;;;;
;;;; [scale] is the function whose signature the tests change. [step] calls it
;;;; every frame and [pick] takes it as a value, so both are callers compiled
;;;; against the signature it starts with — two sites the session has to name
;;;; after the change, and one the running program has to stop at rather than
;;;; call. [lonely] has no caller at all, so changing its signature leaves
;;;; nothing behind.
;;;;
;;;; The frame loop's `skip-frame' restart is what the break buffer resumes
;;;; with once [step] is compiled again. Without it a stale call would have
;;;; nowhere to go but the exit.
(import agent "vendor:agent")

(defonce ticks i64)
(defonce seen i64)

(defn scale [x i64] i64 (* x 2))

(defn step [] i64
  (set ticks (+ ticks 1))
  (set seen (scale ticks))
  seen)

(defn pick [] (Fn [i64] i64) scale)

(defn lonely [x i64] i64 x)

(defn main [] i32
  (agent/start "/tmp/flan-dev-stale-fallback.sock")
  (dotimes [i 6000]
    (agent/wait 5)
    (restart-case (step)
      (skip-frame [] 0)))
  0)

;;; A stale call inside a handler-bind clause that handles StaleCall. The body's
;;; call to [scale] signals, the clause runs, and the clause's own call to
;;; [scale] signals again — which reaches the handlers outside this
;;; handler-bind and not the clause itself, so it stops in the break buffer
;;; rather than recursing until the stack runs out. The clause is a lifted
;;; function, and the stale list names it as [guarded].
(defn guarded [] i64
  (handler-bind [(StaleCall [c] (set seen (scale 1)))]
    (scale 5)))