Apply an untested fix for ghc-7.8

+ Some minor formatting fixes.
+ Add IHaskell.Display.Widgets.Types to hindent ignored_files.
+ Remove some extensions and unused imports.

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

@@ -12,12 +12,10 @@ CheckBox,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
 import           Data.Aeson
 import           Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
 import           Data.Text (Text)
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets

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

@@ -12,7 +12,6 @@ ToggleButton,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
 import           Data.Aeson
 import           Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)

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

@@ -12,11 +12,8 @@ ValidWidget,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
 import           Data.Aeson
-import           Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
-import           Data.Text (Text)
 import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display

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

@@ -12,19 +12,14 @@ Box,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
 import           Data.Aeson
-import           Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
-import           Data.Text (Text)
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets
 import           IHaskell.IPython.Message.UUID as U
 
 import           IHaskell.Display.Widgets.Types
-import           IHaskell.Display.Widgets.Common
 
 -- | A 'Box' represents a Box widget from IPython.html.widgets.
 type Box = IPythonWidget BoxType

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

@@ -12,11 +12,8 @@ FlexBox,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
 import           Data.Aeson
-import           Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
-import           Data.Text (Text)
 import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display

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

@@ -12,11 +12,8 @@ PlaceProxy,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
 import           Data.Aeson
-import           Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
-import           Data.Text (Text)
 import           Data.Vinyl (Rec(..), (<+>))
 import           Data.Vinyl.Lens (rput)
 

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

@@ -12,11 +12,8 @@ ProxyWidget,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
 import           Data.Aeson
-import           Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
-import           Data.Text (Text)
 import           Data.Vinyl (Rec(..), (<+>))
 import           Data.Vinyl.Lens (rput)
 

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

@@ -12,13 +12,11 @@ Accordion,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
 import           Data.Aeson
 import           Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
 import qualified Data.Scientific as Sci
 import           Data.Text (Text)
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets

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

@@ -12,13 +12,11 @@ TabWidget,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
 import           Data.Aeson
 import           Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
 import qualified Data.Scientific as Sci
 import           Data.Text (Text)
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets

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

@@ -12,7 +12,7 @@ Button,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
+import           Control.Monad (when)
 import           Data.Aeson
 import           Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)

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

@@ -5,12 +5,14 @@
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE AutoDeriveTypeable #-}
+{-# LANGUAGE DeriveDataTypeable #-}
 
 module IHaskell.Display.Widgets.Common where
 
 import           Data.Aeson
 import           Data.Aeson.Types (emptyObject)
 import           Data.Text (pack, Text)
+import           Data.Typeable (Typeable)
 
 import           IHaskell.Display (IHaskellWidget)
 import           IHaskell.Eval.Widgets (widgetSendClose)
@@ -99,7 +101,7 @@ closeWidget :: IHaskellWidget w => w -> IO ()
 closeWidget w = widgetSendClose w emptyObject
 
 newtype PixCount = PixCount Integer
-  deriving (Num, Ord, Eq, Enum)
+  deriving (Num, Ord, Eq, Enum, Typeable)
 
 instance ToJSON PixCount where
   toJSON (PixCount x) = toJSON . pack $ show x ++ "px"
@@ -202,7 +204,7 @@ instance ToJSON BarStyleValue where
 data ImageFormatValue = PNG
                       | SVG
                       | JPG
-  deriving Eq
+  deriving (Eq, Typeable)
 
 instance Show ImageFormatValue where
   show PNG = "png"

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

@@ -13,13 +13,11 @@ BoundedFloatText,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
 import qualified Data.Scientific as Sci
 import           Data.Text (Text)
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets

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

@@ -12,13 +12,8 @@ FloatProgress,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Exception (throw, ArithException(LossOfPrecision))
-import           Control.Monad (when, join)
 import           Data.Aeson
-import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
-import qualified Data.Scientific as Sci
-import           Data.Text (Text)
 import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display

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

@@ -12,7 +12,6 @@ FloatSlider,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)

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

@@ -13,8 +13,6 @@ FloatRangeSlider,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Exception (throw, ArithException(LossOfPrecision))
-import           Control.Monad (when, join, void)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)

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

@@ -12,13 +12,11 @@ FloatText,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
 import qualified Data.Scientific as Sci
 import           Data.Text (Text)
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets

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

@@ -12,12 +12,9 @@ ImageWidget,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
 import           Data.Aeson
-import           Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
 import           Data.Monoid (mempty)
-import           Data.Text (Text)
 import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display

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

@@ -12,13 +12,11 @@ BoundedIntText,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
 import qualified Data.Scientific as Sci
 import           Data.Text (Text)
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets

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

@@ -12,13 +12,8 @@ IntProgress,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Exception (throw, ArithException(LossOfPrecision))
-import           Control.Monad (when, join)
 import           Data.Aeson
-import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
-import qualified Data.Scientific as Sci
-import           Data.Text (Text)
 import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display

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

@@ -12,7 +12,6 @@ IntSlider,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)

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

@@ -12,7 +12,6 @@ IntRangeSlider,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)

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

@@ -12,13 +12,11 @@ IntText,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
 import qualified Data.Scientific as Sci
 import           Data.Text (Text)
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets

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

-{-# LANGUAGE DataKinds #-}
 {-# LANGUAGE TypeFamilies #-}
-{-# LANGUAGE ConstraintKinds #-}
-{-# LANGUAGE UndecidableInstances #-}
-{-# LANGUAGE GADTs #-}
+{-# LANGUAGE DataKinds #-}
 {-# LANGUAGE TypeOperators #-}
+{-# LANGUAGE GADTs #-}
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE UndecidableInstances #-}
 {-# LANGUAGE PolyKinds #-}
-{-# LANGUAGE KindSignatures #-}
-{-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE PatternSynonyms #-}
 
 module IHaskell.Display.Widgets.Interactive (interactive, uncurryHList, Rec(..), Argument(..)) where
 
@@ -25,7 +22,7 @@ import           IHaskell.Display
 
 import           IHaskell.Display.Widgets.Types
 import           IHaskell.Display.Widgets.Common
-import qualified IHaskell.Display.Widgets.Singletons as S (SField(..), Field(..))
+import qualified IHaskell.Display.Widgets.Singletons as S (SField, Field(..))
 
 import           IHaskell.Display.Widgets.Box.FlexBox
 import           IHaskell.Display.Widgets.Bool.CheckBox
@@ -44,10 +41,6 @@ data WidgetConf a where
               a
               -> WidgetConf a
 
-newtype WrappedConstructor a =
-          WrappedConstructor
-            { wrappedConstructor :: IO (IPythonWidget (SuitableWidget a)) }
-
  
 type family WithTypes (ts :: [*]) (r :: *) :: * where
         WithTypes '[] r = r
@@ -70,8 +63,6 @@ newtype EventSetter a = EventSetter (IPythonWidget (SuitableWidget a) -> IO () -
 
 newtype Initializer a = Initializer (IPythonWidget (SuitableWidget a) -> Argument a -> IO ())
 
-newtype Trigger a = Trigger (IPythonWidget (SuitableWidget a) -> IO ())
-
  
 data RequiredWidget a where
         RequiredWidget ::
@@ -107,11 +98,8 @@ extractGetter (WidgetConf wr) = Getter $ getValue wr
 extractEventSetter :: WidgetConf x -> EventSetter x
 extractEventSetter (WidgetConf wr) = EventSetter $ setEvent wr
 
-extractTrigger :: WidgetConf x -> Trigger x
-extractTrigger (WidgetConf wr) = Trigger $ trigger wr
-
 extractInitializer :: WidgetConf x -> Initializer x
-extractInitializer (WidgetConf wr) = Initializer initializer
+extractInitializer WidgetConf{} = Initializer initializer
 
 createWidget :: Constructor a -> IO (RequiredWidget a)
 createWidget (Constructor con) = fmap RequiredWidget con
@@ -146,7 +134,6 @@ liftToWidgets func rc initvals = do
       getters = rmap extractGetter rc
       eventSetters = rmap extractEventSetter rc
       initializers = rmap extractInitializer rc
-      triggers = rmap extractTrigger rc
 
   bx <- mkFlexBox
   out <- mkOutputWidget
@@ -188,15 +175,9 @@ construct (WrappedWidget cons _ _) = cons
 getValue :: WrappedWidget w h f a -> IPythonWidget w -> IO a
 getValue (WrappedWidget _ _ field) widget = getField widget field
 
-setValue :: WrappedWidget w h f a -> IPythonWidget w -> a -> IO ()
-setValue (WrappedWidget _ _ field) widget = setField widget field
-
 setEvent :: WrappedWidget w h f a -> IPythonWidget w -> IO () -> IO ()
 setEvent (WrappedWidget _ h _) widget = setField widget h
 
-trigger :: WrappedWidget w h f a -> IPythonWidget w -> IO ()
-trigger (WrappedWidget _ h _) = triggerEvent h
-
 class RecAll Attr (WidgetFields (SuitableWidget a)) ToPairs => FromWidget a where
   type SuitableWidget a :: WidgetType
   type SuitableHandler a :: S.Field

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

@@ -18,12 +18,8 @@ module IHaskell.Display.Widgets.Output (
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
 import           Data.Aeson
-import           Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
-import           Data.Text (Text)
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets

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

@@ -12,7 +12,7 @@ Dropdown,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
+import           Control.Monad (void)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)

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

@@ -12,12 +12,11 @@ RadioButtons,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
+import           Control.Monad (when, void)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
 import           Data.Text (Text)
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets

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

@@ -12,13 +12,12 @@ SelectMultiple,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (fmap, join, sequence, void)
+import           Control.Monad (void)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)
 import           Data.Text (Text)
 import qualified Data.Vector as V
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets

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

@@ -12,7 +12,7 @@ ToggleButtons,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join, void)
+import           Control.Monad (void)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)

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

@@ -12,11 +12,8 @@ HTMLWidget,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
 import           Data.Aeson
 import           Data.IORef (newIORef)
-import           Data.Text (Text)
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets

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

@@ -12,11 +12,8 @@ LatexWidget,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
 import           Data.Aeson
 import           Data.IORef (newIORef)
-import           Data.Text (Text)
-import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display
 import           IHaskell.Eval.Widgets

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

@@ -12,11 +12,10 @@ TextWidget,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
+import           Control.Monad (when)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as Map
 import           Data.IORef (newIORef)
-import           Data.Text (Text)
 import           Data.Vinyl (Rec(..), (<+>))
 
 import           IHaskell.Display

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

@@ -12,7 +12,6 @@ TextArea,
 -- To keep `cabal repl` happy when running from the ihaskell repo
 import           Prelude
 
-import           Control.Monad (when, join)
 import           Data.Aeson
 import qualified Data.HashMap.Strict as HM
 import           Data.IORef (newIORef)

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

@@ -61,10 +61,10 @@ module IHaskell.Display.Widgets.Types where
 --
 -- 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.Monad (unless, join, when, void)
 import           Control.Applicative ((<$>))
 import qualified Control.Exception as Ex
-import           Data.Typeable
+import           Data.Typeable (Typeable, TypeRep, typeOf)
 import           Data.IORef (IORef, readIORef, modifyIORef)
 import           Data.Text (Text, pack)
 import           System.IO.Error
@@ -87,7 +87,8 @@ import           GHC.IO.Exception
 import           IHaskell.Eval.Widgets (widgetSendUpdate)
 import           IHaskell.Display (Base64, IHaskellWidget(..))
 import           IHaskell.IPython.Message.UUID
-import           IHaskell.Display.Widgets.Singletons (Field, SField(..))
+
+import           IHaskell.Display.Widgets.Singletons (Field, SField)
 import qualified IHaskell.Display.Widgets.Singletons as S
 import           IHaskell.Display.Widgets.Common
 
@@ -131,7 +132,7 @@ 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
@@ -269,7 +270,7 @@ data WidgetType = ButtonType
                 | TabType
 
 -- Fields associated with a widget
- 
+
 type family WidgetFields (w :: WidgetType) :: [Field] where
         WidgetFields ButtonType =
                                 DOMWidgetClass :++

src/IHaskell/Flags.hs

@@ -102,7 +102,8 @@ kernelDebugFlag = flagNone ["debug"] addDebug "Print debugging output from the k
     addDebug (Args mode prev) = Args mode (KernelDebug : prev)
 
 kernelStackFlag :: Flag Args
-kernelStackFlag = flagNone ["stack"] addStack "Inherit environment from `stack` when it is installed"
+kernelStackFlag = flagNone ["stack"] addStack
+                    "Inherit environment from `stack` when it is installed"
   where
     addStack (Args mode prev) = Args mode (KernelspecUseStack : prev)
 

src/IHaskell/IPython.hs

@@ -190,7 +190,7 @@ installKernelspec replace opts = void $ do
            Nothing   -> []
            Just file -> ["--conf", file])
         ++ ["--ghclib", kernelSpecGhcLibdir opts]
-        ++ ["--stack" | kernelSpecUseStack opts]
+           ++ ["--stack" | kernelSpecUseStack opts]
 
   let kernelSpec = KernelSpec
         { kernelDisplayName = "Haskell"

verify_formatting.py

@@ -52,7 +52,10 @@ for source_dir in ["src", "ipython-kernel", "ihaskell-display"]:
             continue
 
         # Ignore IHaskellPrelude.hs, it uses CPP in weird places
-        ignored_files = ["IHaskellPrelude.hs"]
+        if widget_dir in root:
+            ignored_files = ["Types.hs"]
+        else:
+            ignored_files = ["IHaskellPrelude.hs"]
         for filename in filenames:
             if filename.endswith(".hs") and filename not in ignored_files:
                 sources.append(os.path.join(root, filename))