Make widget messages match with IPywidgets

The ihaskell-widgets should send messages identical to what the
IPywidgets send. This has not been tested as there are some unresolved
issues in IHaskell that surface only if ipywidgets is installed.

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Bool/CheckBox.hs

@@ -40,11 +40,9 @@ mkCheckBox = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.Checkbox"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the image widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Bool/ToggleButton.hs

@@ -45,11 +45,9 @@ mkToggleButton = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.ToggleButton"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the image widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Box/Box.hs

@@ -40,10 +40,9 @@ mkBox = do
   stateIO <- newIORef widgetState
 
   let box = IPythonWidget uuid stateIO
-      initData = object ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.Box"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen box initData $ toJSON widgetState
+  widgetSendOpen box $ toJSON widgetState
 
   -- Return the widget
   return box

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Box/FlexBox.hs

@@ -46,10 +46,9 @@ mkFlexBox = do
   stateIO <- newIORef widgetState
 
   let box = IPythonWidget uuid stateIO
-      initData = object ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.FlexBox"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen box initData $ toJSON widgetState
+  widgetSendOpen box $ toJSON widgetState
 
   -- Return the widget
   return box

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Box/SelectionContainer/Accordion.hs

@@ -41,11 +41,9 @@ mkAccordion = do
   stateIO <- newIORef widgetState
 
   let box = IPythonWidget uuid stateIO
-      initData = object
-                   ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.Accordion"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen box initData $ toJSON widgetState
+  widgetSendOpen box $ toJSON widgetState
 
   -- Return the widget
   return box

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Box/SelectionContainer/Tab.hs

@@ -41,10 +41,9 @@ mkTabWidget = do
   stateIO <- newIORef widgetState
 
   let box = IPythonWidget uuid stateIO
-      initData = object ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.Tab"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen box initData $ toJSON widgetState
+  widgetSendOpen box $ toJSON widgetState
 
   -- Return the widget
   return box

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Button.hs

@@ -49,10 +49,8 @@ mkButton = do
 
   let button = IPythonWidget uuid stateIO
 
-  let initData = object ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.Button"]
-
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen button initData $ toJSON buttonState
+  widgetSendOpen button $ toJSON buttonState
 
   -- Return the button widget
   return button

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Common.hs

@@ -18,6 +18,8 @@ import qualified IHaskell.Display.Widgets.Singletons as S
 
 pattern ViewModule = S.SViewModule
 pattern ViewName = S.SViewName
+pattern ModelModule = S.SModelModule
+pattern ModelName = S.SModelName
 pattern MsgThrottle = S.SMsgThrottle
 pattern Version = S.SVersion
 pattern DisplayHandler = S.SDisplayHandler

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Float/BoundedFloat/BoundedFloatText.hs

@@ -42,13 +42,9 @@ mkBoundedFloatText = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   [ "model_name" .= str "WidgetModel"
-                   , "widget_class" .= str "IPython.BoundedFloatText"
-                   ]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Float/BoundedFloat/FloatProgress.hs

@@ -44,13 +44,9 @@ mkFloatProgress = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   [ "model_name" .= str "WidgetModel"
-                   , "widget_class" .= str "IPython.FloatProgress"
-                   ]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Float/BoundedFloat/FloatSlider.hs

@@ -47,11 +47,9 @@ mkFloatSlider = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.FloatSlider"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Float/BoundedFloatRange/FloatRangeSlider.hs

@@ -50,13 +50,9 @@ mkFloatRangeSlider = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   [ "model_name" .= str "WidgetModel"
-                   , "widget_class" .= str "IPython.FloatRangeSlider"
-                   ]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Float/FloatText.hs

@@ -41,11 +41,9 @@ mkFloatText = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.FloatText"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Image.hs

@@ -46,10 +46,8 @@ mkImageWidget = do
 
   let widget = IPythonWidget uuid stateIO
 
-  let initData = object ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.Image"]
-
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the image widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Int/BoundedInt/BoundedIntText.hs

@@ -41,13 +41,9 @@ mkBoundedIntText = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   [ "model_name" .= str "WidgetModel"
-                   , "widget_class" .= str "IPython.BoundedIntText"
-                   ]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Int/BoundedInt/IntProgress.hs

@@ -44,11 +44,9 @@ mkIntProgress = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.IntProgress"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Int/BoundedInt/IntSlider.hs

@@ -47,11 +47,9 @@ mkIntSlider = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.IntSlider"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Int/BoundedIntRange/IntRangeSlider.hs

@@ -48,13 +48,9 @@ mkIntRangeSlider = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   [ "model_name" .= str "WidgetModel"
-                   , "widget_class" .= str "IPython.IntRangeSlider"
-                   ]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Int/IntText.hs

@@ -41,10 +41,9 @@ mkIntText = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.IntText"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Output.hs

@@ -45,10 +45,9 @@ mkOutputWidget = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object ["model_name" .= str "WidgetModel"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the image widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Selection/Dropdown.hs

@@ -41,11 +41,9 @@ mkDropdown = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.Dropdown"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Selection/RadioButtons.hs

@@ -39,11 +39,9 @@ mkRadioButtons = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.RadioButtons"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Selection/Select.hs

@@ -39,10 +39,9 @@ mkSelect = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.Select"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Selection/SelectMultiple.hs

@@ -40,13 +40,9 @@ mkSelectMultiple = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   [ "model_name" .= str "WidgetModel"
-                   , "widget_class" .= str "IPython.SelectMultiple"
-                   ]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Selection/ToggleButtons.hs

@@ -44,13 +44,9 @@ mkToggleButtons = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   [ "model_name" .= str "WidgetModel"
-                   , "widget_class" .= str "IPython.ToggleButtons"
-                   ]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Singletons.hs

@@ -13,9 +13,11 @@ import           Data.Singletons.TH
 -- Widget properties
 singletons
   [d|
-   
+
   data Field = ViewModule
              | ViewName
+             | ModelModule
+             | ModelName
              | MsgThrottle
              | Version
              | DisplayHandler

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/String/HTML.hs

@@ -37,10 +37,9 @@ mkHTMLWidget = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.HTML"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/String/Latex.hs

@@ -37,10 +37,9 @@ mkLatexWidget = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.Latex"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/String/Text.hs

@@ -41,10 +41,9 @@ mkTextWidget = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.Text"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/String/TextArea.hs

@@ -41,11 +41,9 @@ mkTextArea = do
   stateIO <- newIORef widgetState
 
   let widget = IPythonWidget uuid stateIO
-      initData = object
-                   ["model_name" .= str "WidgetModel", "widget_class" .= str "IPython.Textarea"]
 
   -- Open a comm for this widget, and store it in the kernel state
-  widgetSendOpen widget initData $ toJSON widgetState
+  widgetSendOpen widget $ toJSON widgetState
 
   -- Return the widget
   return widget

ihaskell-display/ihaskell-widgets/src/IHaskell/Display/Widgets/Types.hs

@@ -57,7 +57,7 @@ module IHaskell.Display.Widgets.Types where
 -- To know more about the IPython messaging specification (as implemented in this package) take a
 -- look at the supplied MsgSpec.md.
 --
--- Widgets are not able to do console input, the reason for that can also be found in the messaging
+-- Widgets are not able to do console input, the reason for that can be found in the messaging
 -- specification
 import           Control.Monad (unless, join, when, void, mapM_)
 import           Control.Applicative ((<$>))
@@ -89,7 +89,7 @@ import qualified IHaskell.Display.Widgets.Singletons as S
 import           IHaskell.Display.Widgets.Common
 
 -- Classes from IPython's widget hierarchy. Defined as such to reduce code duplication.
-type WidgetClass = '[S.ViewModule, S.ViewName, S.MsgThrottle, S.Version,
+type WidgetClass = '[S.ViewModule, S.ViewName, S.ModelModule, S.ModelName, S.MsgThrottle, S.Version,
   S.DisplayHandler]
 
 type DOMWidgetClass = WidgetClass :++ '[S.Visible, S.CSS, S.DOMClasses, S.Width, S.Height, S.Padding,
@@ -128,10 +128,12 @@ type BoxClass = DOMWidgetClass :++ '[S.Children, S.OverflowX, S.OverflowY, S.Box
 type SelectionContainerClass = BoxClass :++ '[S.Titles, S.SelectedIndex, S.ChangeHandler]
 
 -- Types associated with Fields.
- 
+
 type family FieldType (f :: Field) :: * where
         FieldType S.ViewModule = Text
         FieldType S.ViewName = Text
+        FieldType S.ModelModule = Text
+        FieldType S.ModelName = Text
         FieldType S.MsgThrottle = Integer
         FieldType S.Version = Integer
         FieldType S.DisplayHandler = IO ()
@@ -339,6 +341,12 @@ instance ToPairs (Attr S.ViewModule) where
 instance ToPairs (Attr S.ViewName) where
   toPairs x = ["_view_name" .= toJSON x]
 
+instance ToPairs (Attr S.ModelModule) where
+  toPairs x = ["_model_module" .= toJSON x]
+
+instance ToPairs (Attr S.ModelName) where
+  toPairs x = ["_model_name" .= toJSON x]
+
 instance ToPairs (Attr S.MsgThrottle) where
   toPairs x = ["msg_throttle" .= toJSON x]
 
@@ -591,6 +599,8 @@ reflect = fromSing
 defaultWidget :: FieldType S.ViewName -> Rec Attr WidgetClass
 defaultWidget viewName = (ViewModule =:: "")
                          :& (ViewName =:: viewName)
+                         :& (ModelModule =:: "")
+                         :& (ModelName =:: "WidgetModel")
                          :& (MsgThrottle =:+ 3)
                          :& (Version =:: 0)
                          :& (DisplayHandler =:: return ())

ipython-kernel/src/IHaskell/IPython/Message/Parser.hs

@@ -159,9 +159,10 @@ inputReplyParser = requestParser $ \obj -> do
 commOpenParser :: LByteString -> Message
 commOpenParser = requestParser $ \obj -> do
   uuid <- obj .: "comm_id"
-  name <- obj .: "target_name"
+  targetName <- obj .: "target_name"
+  targetModule <- obj .: "target_module"
   value <- obj .: "data"
-  return $ CommOpen noHeader name uuid value
+  return $ CommOpen noHeader targetName targetModule uuid value
 
 commDataParser :: LByteString -> Message
 commDataParser = requestParser $ \obj -> do

ipython-kernel/src/IHaskell/IPython/Message/Writer.hs

@@ -97,7 +97,11 @@ instance ToJSON Message where
     object ["prompt" .= prompt]
 
   toJSON req@CommOpen{} =
-    object ["comm_id" .= commUuid req, "target_name" .= commTargetName req, "data" .= commData req]
+    object [ "comm_id" .= commUuid req
+           , "target_name" .= commTargetName req
+           , "target_module" .= commTargetModule req
+           , "data" .= commData req
+           ]
 
   toJSON req@CommData{} =
     object ["comm_id" .= commUuid req, "data" .= commData req]

ipython-kernel/src/IHaskell/IPython/Types.hs

@@ -375,6 +375,7 @@ data Message =
                CommOpen
                  { header :: MessageHeader
                  , commTargetName :: String
+                 , commTargetModule :: String
                  , commUuid :: UUID
                  , commData :: Value
                  }

src/IHaskell/Eval/Widgets.hs

@@ -52,9 +52,8 @@ widgetSend :: IHaskellWidget a
 widgetSend msgType widget value = queue $ msgType (Widget widget) value
 
 -- | Send a message to open a comm
-widgetSendOpen :: IHaskellWidget a => a -> Value -> Value -> IO ()
-widgetSendOpen widget initVal stateVal =
-  queue $ Open (Widget widget) initVal stateVal
+widgetSendOpen :: IHaskellWidget a => a -> Value -> IO ()
+widgetSendOpen = widgetSend Open
 
 -- | Send a state update message
 widgetSendUpdate :: IHaskellWidget a => a -> Value -> IO ()
@@ -93,8 +92,9 @@ handleMessage :: (Message -> IO ())
               -> IO KernelState
 handleMessage send replyHeader state msg = do
   case msg of
-    Open widget initVal stateVal -> do
-      let target = targetName widget
+    Open widget value -> do
+      let target_name = targetName widget
+          target_module = targetModule widget
           uuid = getCommUUID widget
           present = isJust $ Map.lookup uuid oldComms
 
@@ -109,12 +109,9 @@ handleMessage send replyHeader state msg = do
       if present
         then return state
         else do
-          -- Send the comm open
+          -- Send the comm open, with the initial state
           header <- dupHeader replyHeader CommOpenMessage
-          send $ CommOpen header target uuid initVal
-
-          -- Initial state update
-          communicate . toJSON $ UpdateState stateVal
+          send $ CommOpen header target_name target_module uuid value
 
           -- Send anything else the widget requires.
           open widget communicate
@@ -123,8 +120,7 @@ handleMessage send replyHeader state msg = do
           return newState
 
     Close widget value -> do
-      let target = targetName widget
-          uuid = getCommUUID widget
+      let uuid = getCommUUID widget
           present = isJust $ Map.lookup uuid oldComms
 
           newComms = Map.delete uuid $ openComms state

src/IHaskell/Types.hs

@@ -65,11 +65,15 @@ class IHaskellDisplay a where
 
 -- | Display as an interactive widget.
 class IHaskellDisplay a => IHaskellWidget a where
-  -- | Output target name for this widget. The actual input parameter should be ignored. By default
+  -- | Target name for this widget. The actual input parameter should be ignored. By default
   -- evaluate to "ipython.widget", which is used by IPython for its backbone widgets.
   targetName :: a -> String
   targetName _ = "ipython.widget"
 
+  -- | Target module for this widget. Evaluates to an empty string by default.
+  targetModule :: a -> String
+  targetModule _ = ""
+
   -- | Get the uuid for comm associated with this widget. The widget is responsible for storing the
   -- UUID during initialization.
   getCommUUID :: a -> UUID
@@ -102,6 +106,7 @@ instance IHaskellDisplay Widget where
 
 instance IHaskellWidget Widget where
   targetName (Widget widget) = targetName widget
+  targetModule (Widget widget) = targetModule widget
   getCommUUID (Widget widget) = getCommUUID widget
   open (Widget widget) = open widget
   comm (Widget widget) = comm widget
@@ -185,11 +190,10 @@ data LintStatus = LintOn
   deriving (Eq, Show)
 
 -- | Send JSON objects with specific formats
-data WidgetMsg = Open Widget Value Value
+data WidgetMsg = Open Widget Value
                |
                -- ^ Cause the interpreter to open a new comm, and register the associated widget in
-               -- the kernelState. Also sends a Value with comm_open, and then sends an initial
-               -- state update Value.
+               -- the kernelState. Also sends an initial state Value with comm_open.
                 Update Widget Value
                |
                -- ^ Cause the interpreter to send a comm_msg containing a state update for the