restructure a bit to make the GLFW-initialisation code its own separate structure/file, and so we can use shell.sml for running program in different ways

dotscape.mlb

@@ -71,5 +71,6 @@ imperative-shell/input-callbacks.sml
 imperative-shell/update-thread.sml
 imperative-shell/file-thread.sml
 imperative-shell/draw-thread.sml
+imperative-shell/init-glfw.sml
 
 imperative-shell/shell.sml

imperative-shell/init-glfw.sml

@@ -0,0 +1,63 @@
+structure InitGlfw =
+struct
+  open CML
+
+  fun init () =
+    let
+      (* Set up GLFW. *)
+      val _ = Glfw.init ()
+      val _ = Glfw.windowHint (Glfw.CONTEXT_VERSION_MAJOR (), 3)
+      val _ = Glfw.windowHint (Glfw.DEPRECATED (), Glfw.FALSE ())
+      val _ = Glfw.windowHint (Glfw.SAMPLES (), 0)
+      val window =
+        Glfw.createWindow
+          (Constants.windowWidth, Constants.windowHeight, "Dotscape")
+      val _ = Glfw.makeContextCurrent window
+      val _ = Gles3.loadGlad ()
+
+      val initialModel = AppInit.fromWindowWidthAndHeight
+        ( Constants.windowWidth
+        , Constants.windowHeight
+        , Constants.initialWidthClickPoints
+        , Constants.initialHeightClickPoints
+        )
+
+      val graphLines = GraphLines.generate initialModel
+      val graphDrawObject = AppDraw.initGraphLines ()
+      val _ = AppDraw.uploadGraphLines (graphDrawObject, graphLines)
+
+      val dotDrawObject = AppDraw.initDot ()
+      val squareDrawObject = AppDraw.initSquares ()
+
+      val modalTextDrawObject = AppDraw.initModalText ()
+
+      val inputMailbox = Mailbox.mailbox ()
+      val drawMailbox = Mailbox.mailbox ()
+      val fileMailbox = Mailbox.mailbox ()
+
+      val _ = InputCallbacks.registerCallbacks (window, inputMailbox)
+
+      val _ = CML.spawn (fn () =>
+        UpdateThread.run (inputMailbox, drawMailbox, fileMailbox, initialModel))
+
+      val _ = CML.spawn (fn () =>
+        DrawThread.run
+          ( drawMailbox
+          , window
+          , graphDrawObject
+          , Vector.length graphLines div 2
+          , dotDrawObject
+          , 0
+          , squareDrawObject
+          , 0
+          , modalTextDrawObject
+          , 0
+          ))
+
+      val _ = CML.spawn (fn () => FileThread.run (fileMailbox, inputMailbox))
+    in
+      ()
+    end
+
+  fun main () = RunCML.doit (init, NONE)
+end

imperative-shell/shell.sml

@@ -1,63 +1,6 @@
 structure Shell =
 struct
-  open CML
+  fun main () = InitGlfw.main ()
-
-  fun main () =
-    let
-      (* Set up GLFW. *)
-      val _ = Glfw.init ()
-      val _ = Glfw.windowHint (Glfw.CONTEXT_VERSION_MAJOR (), 3)
-      val _ = Glfw.windowHint (Glfw.DEPRECATED (), Glfw.FALSE ())
-      val _ = Glfw.windowHint (Glfw.SAMPLES (), 0)
-      val window =
-        Glfw.createWindow
-          (Constants.windowWidth, Constants.windowHeight, "Dotscape")
-      val _ = Glfw.makeContextCurrent window
-      val _ = Gles3.loadGlad ()
-
-      val initialModel = AppInit.fromWindowWidthAndHeight
-        ( Constants.windowWidth
-        , Constants.windowHeight
-        , Constants.initialWidthClickPoints
-        , Constants.initialHeightClickPoints
-        )
-
-      val graphLines = GraphLines.generate initialModel
-      val graphDrawObject = AppDraw.initGraphLines ()
-      val _ = AppDraw.uploadGraphLines (graphDrawObject, graphLines)
-
-      val dotDrawObject = AppDraw.initDot ()
-      val squareDrawObject = AppDraw.initSquares ()
-
-      val modalTextDrawObject = AppDraw.initModalText ()
-
-      val inputMailbox = Mailbox.mailbox ()
-      val drawMailbox = Mailbox.mailbox ()
-      val fileMailbox = Mailbox.mailbox ()
-
-      val _ = InputCallbacks.registerCallbacks (window, inputMailbox)
-
-      val _ = CML.spawn (fn () =>
-        UpdateThread.run (inputMailbox, drawMailbox, fileMailbox, initialModel))
-
-      val _ = CML.spawn (fn () =>
-        DrawThread.run
-          ( drawMailbox
-          , window
-          , graphDrawObject
-          , Vector.length graphLines div 2
-          , dotDrawObject
-          , 0
-          , squareDrawObject
-          , 0
-          , modalTextDrawObject
-          , 0
-          ))
-
-      val _ = CML.spawn (fn () => FileThread.run (fileMailbox, inputMailbox))
-    in
-      ()
-    end
 end
 
-val _ = RunCML.doit (Shell.main, NONE)
+val _ = Shell.main ()