Subscribe to game loop, UI now does (yoda I am)

src/age_of_sail/core.clj

@@ -7,6 +7,11 @@
 (def tickrate 100)
 (def hardcoded-wind [0.1 3.0]) ;; A strong easternly wind!
 (defonce ships (atom []))
+(def hooks (atom '()))
+(defn subscribe!
+  "Adds a hook to the hooks"
+  [f]
+  (swap! hooks conj f))
 
 (defn ship-names
   "Gets the names from a list of ships"
@@ -49,13 +54,16 @@
   (doseq [ship ships]
     (-> ship (physics-step hardcoded-wind))))
 
+(subscribe! #(tick @ships))
+
 ;; Simulation controls
 (defonce program (atom :stopped))
 (defn game-loop
   []
   (while (#{:running :paused} @program)
     (when (= :running @program)
-      (tick @ships))
+      (doseq [hook @hooks]
+        (hook)))
     (Thread/sleep (quot 1000 tickrate)))
   (when-not (compare-and-set! program :killed :stopped)
     (throw "Error: tried to stop a program that wasn't killed!")))
@@ -80,6 +88,13 @@
   (fn [& _] (f)))
 
 (def tracked-ship (atom nil))
+(def ship-pos (b/notify-later))
+(defn update-pos
+  []
+  (let [ship @tracked-ship]
+    (when ship
+      (b/notify ship-pos (:position @ship)))))
+(subscribe! update-pos)
 
 (defn simulation-controls
   []
@@ -106,16 +121,14 @@
     (flow-panel :items ["Ship Name" name])))
 
 (defn format-position
-  [ship]
+  [[x y]]
-  (apply format "X: %.2f Y: %.2f" (:position @ship)))
+  (format "X: %.2f Y: %.2f" x y))
 
 (defn ship-info
   []
   (let [panel (vertical-panel :visible? false)
         position (label)]
-    (b/bind tracked-ship (b/some identity)
+    (b/bind ship-pos (b/transform format-position) (b/property position :text))
-            (b/tee
-             (b/bind (b/transform format-position) (b/value position))))
     (add! panel (flow-panel :items ["Position" position]))
     panel))
 
@@ -134,6 +147,7 @@
       show!)))
 
 (defn -main
-  [args]
+  []
   (start-program)
   (show-ui))
+