done with scaffolding for file mailbox; next, send message to file mailbox to export and import, and handle these messages properly from the file mailbox

imperative-shell/update-thread.sml

@@ -3,6 +3,7 @@ sig
   val run:
       InputMessage.t Mailbox.mbox
     * DrawMessage.t Mailbox.mbox
+    * FileMessage.t Mailbox.mbox
     * AppType.app_type
     -> unit
 end
@@ -12,21 +13,21 @@ struct
   open CML
   open UpdateMessage
 
-  fun handleMsg (drawMailbox, updateMsg) =
+  fun handleMsg (drawMailbox, fileMailbox, updateMsg) =
     case updateMsg of
       DRAW drawMsg => Mailbox.send (drawMailbox, drawMsg)
-    | FILE fileMsg => ()
+    | FILE fileMsg => Mailbox.send (fileMailbox, fileMsg)
     | NO_MAILBOX => ()
 
-  fun loop (inputMailbox, drawMailbox, model) =
+  fun loop (inputMailbox, drawMailbox, fileMailbox, model) =
     let
       val inputMsg = Mailbox.recv inputMailbox
       val (model, updateMsg) = AppUpdate.update (model, inputMsg)
-      val _ = handleMsg (drawMailbox, updateMsg)
+      val _ = handleMsg (drawMailbox, fileMailbox, updateMsg)
     in
-      loop (inputMailbox, drawMailbox, model)
+      loop (inputMailbox, drawMailbox, fileMailbox, model)
     end
 
-  fun run (inputMailbox, drawMailbox, initial) =
-    loop (inputMailbox, drawMailbox, initial)
+  fun run (inputMailbox, drawMailbox, fileMailbox, initial) =
+    loop (inputMailbox, drawMailbox, fileMailbox, initial)
 end