Merge pull request #444 from gibiansky/enforce-proper-formatting

Enforce proper formatting

.gitignore

@@ -16,3 +16,6 @@ todo
 profile/profile.tar
 .cabal-sandbox
 cabal.sandbox.config
+.tmp1
+.tmp2
+.tmp3

.travis.yml

@@ -14,6 +14,7 @@ before_install:
  - travis_retry sudo apt-get update
  - travis_retry sudo apt-get install cabal-install-$CABALVER ghc-$GHCVER # see note about happy/alex
  - travis_retry sudo apt-get install libmagic-dev
+ - travis_retry sudo apt-get install python3
  - travis_retry git clone http://www.github.com/zeromq/zeromq4-x.git libzmq
  - export OLDPWD=$(pwd) && cd libzmq && travis_retry ./autogen.sh && travis_retry ./configure && make && travis_retry sudo make install && travis_retry sudo ldconfig && cd $OLDPWD
  - export PATH=/opt/ghc/$GHCVER/bin:/opt/cabal/$CABALVER/bin:$HOME/.cabal/bin:$PATH
@@ -34,6 +35,8 @@ install:
  - |
    if [ ${GHCVER%.*} = "7.8" ]; then
      travis_retry cabal install arithmoi==0.4.* -fllvm
+     travis_retry git clone http://www.github.com/gibiansky/hindent
+     cd hindent && cabal install && cd ..
    fi
 
 # Here starts the actual work to be performed for the package under test; any command which exits with a non-zero exit code causes the build to fail.
@@ -47,7 +50,10 @@ script:
 # Build and run the test suite
  - travis_retry cabal configure --enable-tests
  - travis_retry cabal test --show-details=always
-
+ - |
+   if [ ${GHCVER%.*} = "7.8" ]; then
+    ./verify_formatting.py
+   fi
  - cabal sdist
 
 # The following scriptlet checks that the resulting source distribution can be built & installed

src/IHaskell/BrokenPackages.hs

 {-# LANGUAGE OverloadedStrings, NoImplicitPrelude, FlexibleContexts #-}
+
 module IHaskell.BrokenPackages (getBrokenPackages) where
 
 import           ClassyPrelude hiding ((<|>))
@@ -11,17 +12,13 @@ import Data.String.Utils (startswith)
 
 import           Shelly
 
-data BrokenPackage = BrokenPackage {
-        packageID :: String,
-        brokenDeps :: [String]
-      }
+data BrokenPackage = BrokenPackage { packageID :: String, brokenDeps :: [String] }
 
 instance Show BrokenPackage where
   show = packageID
 
--- | Get a list of broken packages.
--- This function internally shells out to `ghc-pkg`, and parses the output
--- in order to determine what packages are broken.
+-- | Get a list of broken packages. This function internally shells out to `ghc-pkg`, and parses the
+-- output in order to determine what packages are broken.
 getBrokenPackages :: IO [String]
 getBrokenPackages = shelly $ do
   silently $ errExit False $ run "ghc-pkg" ["check"]
@@ -32,7 +29,8 @@ getBrokenPackages = shelly $ do
                        startswith "  dependency" str
       ghcPkgOutput = unlines . filter rightStart . lines $ unpack checkOut
 
-  return $ case parse (many check) "ghc-pkg output" ghcPkgOutput of
+  return $
+    case parse (many check) "ghc-pkg output" ghcPkgOutput of
       Left err   -> []
       Right pkgs -> map show pkgs
 

src/IHaskell/Convert.hs

 -- | Description : mostly reversible conversion between ipynb and lhs 
 module IHaskell.Convert (convert) where
+
 import           Control.Monad.Identity (Identity(Identity), unless, when)
-import IHaskell.Convert.Args (ConvertSpec(ConvertSpec, convertInput, convertLhsStyle, convertOutput, convertOverwriteFiles, convertToIpynb), fromJustConvertSpec, toConvertSpec)
+import           IHaskell.Convert.Args (ConvertSpec(..), fromJustConvertSpec, toConvertSpec)
 import           IHaskell.Convert.IpynbToLhs (ipynbToLhs)
 import           IHaskell.Convert.LhsToIpynb (lhsToIpynb)
 import           IHaskell.Flags (Argument)
@@ -10,12 +11,15 @@ import Text.Printf (printf)
 
 -- | used by @IHaskell convert@
 convert :: [Argument] -> IO ()
-convert args = case fromJustConvertSpec (toConvertSpec args) of
-  ConvertSpec { convertToIpynb = Identity toIpynb,
-                convertInput = Identity inputFile,
-                convertOutput = Identity outputFile,
-                convertLhsStyle = Identity lhsStyle,
-                convertOverwriteFiles = force }
+convert args =
+  case fromJustConvertSpec (toConvertSpec args) of
+    ConvertSpec
+      { convertToIpynb = Identity toIpynb
+      , convertInput = Identity inputFile
+      , convertOutput = Identity outputFile
+      , convertLhsStyle = Identity lhsStyle
+      , convertOverwriteFiles = force
+      }
       | toIpynb -> do
           unless force (failIfExists outputFile)
           lhsToIpynb lhsStyle inputFile outputFile
@@ -29,5 +33,3 @@ failIfExists file = do
   exists <- doesFileExist file
   when exists $ fail $
     printf "File %s already exists. To force supply --force." file
-
-

src/IHaskell/Convert/Args.hs

 -- | Description: interpret flags parsed by "IHaskell.Flags"
-module IHaskell.Convert.Args
-  (ConvertSpec(..),
-   fromJustConvertSpec,
-   toConvertSpec,
-  ) where
+module IHaskell.Convert.Args (ConvertSpec(..), fromJustConvertSpec, toConvertSpec) where
 
 import           Control.Applicative ((<$>))
 import           Control.Monad.Identity (Identity(Identity))
@@ -15,35 +11,36 @@ import IHaskell.Flags (Argument(..), LhsStyle, lhsStyleBird, NotebookFormat(..))
 import           System.FilePath ((<.>), dropExtension, takeExtension)
 import           Text.Printf (printf)
 
-
 -- | ConvertSpec is the accumulator for command line arguments
-data ConvertSpec f = ConvertSpec
-  { convertToIpynb :: f Bool,
-    convertInput :: f FilePath,
-    convertOutput :: f FilePath,
-    convertLhsStyle :: f (LhsStyle T.Text),
-    convertOverwriteFiles :: Bool
+data ConvertSpec f =
+       ConvertSpec
+         { convertToIpynb :: f Bool
+         , convertInput :: f FilePath
+         , convertOutput :: f FilePath
+         , convertLhsStyle :: f (LhsStyle T.Text)
+         , convertOverwriteFiles :: Bool
          }
 
--- | Convert a possibly-incomplete specification for what to convert
--- into one which can be executed. Calls error when data is missing.
+-- | Convert a possibly-incomplete specification for what to convert into one which can be executed.
+-- Calls error when data is missing.
 fromJustConvertSpec :: ConvertSpec Maybe -> ConvertSpec Identity
-fromJustConvertSpec convertSpec = convertSpec {
-        convertToIpynb = Identity toIpynb,
-        convertInput = Identity inputFile,
-        convertOutput = Identity outputFile,
-        convertLhsStyle = Identity $ fromMaybe
-                                        (T.pack <$> lhsStyleBird)
-                                        (convertLhsStyle convertSpec)
+fromJustConvertSpec convertSpec = convertSpec
+  { convertToIpynb = Identity toIpynb
+  , convertInput = Identity inputFile
+  , convertOutput = Identity outputFile
+  , convertLhsStyle = Identity $ fromMaybe (T.pack <$> lhsStyleBird) (convertLhsStyle convertSpec)
   }
   where
     toIpynb = fromMaybe (error "Error: direction for conversion unknown")
                 (convertToIpynb convertSpec)
-    (inputFile, outputFile) = case (convertInput convertSpec, convertOutput convertSpec) of
+    (inputFile, outputFile) =
+      case (convertInput convertSpec, convertOutput convertSpec) of
         (Nothing, Nothing) -> error "Error: no files specified for conversion"
-        (Just i, Nothing) | toIpynb -> (i, dropExtension i <.> "ipynb")
+        (Just i, Nothing)
+          | toIpynb -> (i, dropExtension i <.> "ipynb")
           | otherwise -> (i, dropExtension i <.> "lhs")
-        (Nothing, Just o) | toIpynb -> (dropExtension o <.> "lhs", o)
+        (Nothing, Just o)
+          | toIpynb -> (dropExtension o <.> "lhs", o)
           | otherwise -> (dropExtension o <.> "ipynb", o)
         (Just i, Just o) -> (i, o)
 
@@ -53,10 +50,8 @@ isFormatSpec (ConvertToFormat _) = True
 isFormatSpec (ConvertFromFormat _) = True
 isFormatSpec _ = False
 
-
 toConvertSpec :: [Argument] -> ConvertSpec Maybe
-toConvertSpec args = mergeArgs otherArgs
-                                (mergeArgs formatSpecArgs initialConvertSpec)
+toConvertSpec args = mergeArgs otherArgs (mergeArgs formatSpecArgs initialConvertSpec)
   where
     (formatSpecArgs, otherArgs) = partition isFormatSpec args
     initialConvertSpec = ConvertSpec Nothing Nothing Nothing Nothing False
@@ -68,40 +63,39 @@ mergeArg ::  Argument -> ConvertSpec Maybe -> ConvertSpec Maybe
 mergeArg OverwriteFiles convertSpec = convertSpec { convertOverwriteFiles = True }
 mergeArg (ConvertLhsStyle lhsStyle) convertSpec
   | Just previousLhsStyle <- convertLhsStyle convertSpec,
-    previousLhsStyle /= fmap T.pack lhsStyle = error $ printf
-                                              "Conflicting lhs styles requested: <%s> and <%s>"
-                                              (show lhsStyle) (show previousLhsStyle)
+    previousLhsStyle /= fmap T.pack lhsStyle
+  = error $ printf "Conflicting lhs styles requested: <%s> and <%s>" (show lhsStyle)
+              (show previousLhsStyle)
   | otherwise = convertSpec { convertLhsStyle = Just (T.pack <$> lhsStyle) }
 mergeArg (ConvertFrom inputFile) convertSpec
   | Just previousInputFile <- convertInput convertSpec,
-    previousInputFile /= inputFile = error $ printf "Multiple input files specified: <%s> and <%s>"
-                                              inputFile previousInputFile
-  | otherwise = convertSpec {
-          convertInput = Just inputFile,
-          convertToIpynb = case (convertToIpynb convertSpec, fromExt inputFile) of
+    previousInputFile /= inputFile
+  = error $ printf "Multiple input files specified: <%s> and <%s>" inputFile previousInputFile
+  | otherwise = convertSpec
+      { convertInput = Just inputFile
+      , convertToIpynb = case (convertToIpynb convertSpec, fromExt inputFile) of
         (prev, Nothing)    -> prev
-                              (prev @ (Just _), _) -> prev
+        (prev@(Just _), _) -> prev
         (Nothing, format)  -> fmap (== LhsMarkdown) format
       }
-
 mergeArg (ConvertTo outputFile) convertSpec
   | Just previousOutputFile <- convertOutput convertSpec,
-    previousOutputFile /= outputFile = error $ printf "Multiple output files specified: <%s> and <%s>"
-                                              outputFile previousOutputFile
-  | otherwise = convertSpec {
-          convertOutput = Just outputFile,
-          convertToIpynb = case (convertToIpynb convertSpec, fromExt outputFile) of
+    previousOutputFile /= outputFile
+  = error $ printf "Multiple output files specified: <%s> and <%s>" outputFile previousOutputFile
+  | otherwise = convertSpec
+      { convertOutput = Just outputFile
+      , convertToIpynb = case (convertToIpynb convertSpec, fromExt outputFile) of
         (prev, Nothing)    -> prev
-                              (prev @ (Just _), _) -> prev
+        (prev@(Just _), _) -> prev
         (Nothing, format)  -> fmap (== IpynbFile) format
       }
-
 mergeArg unexpectedArg _ = error $ "IHaskell.Convert.mergeArg: impossible argument: "
                                    ++ show unexpectedArg
 
 -- | Guess the format based on the file extension.
 fromExt :: FilePath -> Maybe NotebookFormat
-fromExt s = case map toLower (takeExtension s) of
+fromExt s =
+  case map toLower (takeExtension s) of
     ".lhs"   -> Just LhsMarkdown
     ".ipynb" -> Just IpynbFile
     _        -> Nothing

src/IHaskell/Convert/IpynbToLhs.hs

 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ScopedTypeVariables #-}
+
 module IHaskell.Convert.IpynbToLhs (ipynbToLhs) where
 
 import           Control.Applicative ((<$>))
@@ -12,7 +13,7 @@ import qualified Data.Text.Lazy as T (concat, fromStrict, Text, unlines)
 import qualified Data.Text.Lazy.IO as T (writeFile)
 import           Data.Vector (Vector)
 import qualified Data.Vector as V (map, mapM, toList)
-import IHaskell.Flags (LhsStyle(lhsBeginCode, lhsBeginOutput, lhsCodePrefix, lhsEndCode, lhsEndOutput, lhsOutputPrefix))
+import           IHaskell.Flags (LhsStyle(..))
 
 ipynbToLhs :: LhsStyle T.Text
            -> FilePath -- ^ the filename of an ipython notebook
@@ -22,8 +23,7 @@ ipynbToLhs sty from to = do
   Just (js :: Object) <- decode <$> L.readFile from
   case M.lookup "cells" js of
     Just (Array cells) ->
-      T.writeFile to $ T.unlines $ V.toList
-        $ V.map (\(Object y) -> convCell sty y) cells
+      T.writeFile to $ T.unlines $ V.toList $ V.map (\(Object y) -> convCell sty y) cells
     _ -> error "IHaskell.Convert.ipynbTolhs: json does not follow expected schema"
 
 concatWithPrefix :: T.Text -- ^ the prefix to add to every line
@@ -35,19 +35,21 @@ toStr :: Value -> Maybe T.Text
 toStr (String x) = Just (T.fromStrict x)
 toStr _ = Nothing
 
--- | @convCell sty cell@ converts a single cell in JSON into text suitable
--- for the type of lhs file described by the @sty@
+-- | @convCell sty cell@ converts a single cell in JSON into text suitable for the type of lhs file
+-- described by the @sty@
 convCell :: LhsStyle T.Text -> Object -> T.Text
 convCell _sty object
   | Just (String "markdown") <- M.lookup "cell_type" object,
     Just (Array xs) <- M.lookup "source" object,
-    ~ (Just s) <- concatWithPrefix "" xs = s
+    ~(Just s) <- concatWithPrefix "" xs
+  = s
 convCell sty object
   | Just (String "code") <- M.lookup "cell_type" object,
     Just (Array i) <- M.lookup "source" object,
     Just (Array o) <- M.lookup "outputs" object,
-     ~ (Just i) <- concatWithPrefix (lhsCodePrefix sty) i,
-      o <- fromMaybe mempty (convOutputs sty o) = "\n" <>
+    ~(Just i) <- concatWithPrefix (lhsCodePrefix sty) i,
+    o <- fromMaybe mempty (convOutputs sty o)
+  = "\n" <>
     lhsBeginCode sty <> i <> lhsEndCode sty <> "\n" <> o <> "\n"
 convCell _ _ = "IHaskell.Convert.convCell: unknown cell"
 

src/IHaskell/Convert/LhsToIpynb.hs

 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE CPP #-}
+
 module IHaskell.Convert.LhsToIpynb (lhsToIpynb) where
 
 import           Control.Applicative ((<$>))
@@ -19,7 +20,9 @@ lhsToIpynb sty from to = do
   classed <- classifyLines sty . T.lines <$> T.readFile from
   L.writeFile to . encode . encodeCells $ groupClassified classed
 
-data CellLine a = CodeLine a | OutputLine a | MarkdownLine a
+data CellLine a = CodeLine a
+                | OutputLine a
+                | MarkdownLine a
   deriving Show
 
 isCode :: CellLine t -> Bool
@@ -38,37 +41,39 @@ isEmptyMD ::  (Eq a, Monoid a) => CellLine a -> Bool
 isEmptyMD (MarkdownLine a) = a == mempty
 isEmptyMD _ = False
 
-
 untag :: CellLine t -> t
 untag (CodeLine a) = a
 untag (OutputLine a) = a
 untag (MarkdownLine a) = a
 
-data Cell a = Code a a | Markdown a
-            deriving (Show)
+data Cell a = Code a a
+            | Markdown a
+  deriving Show
 
 encodeCells :: [Cell [T.Text]] -> Value
 encodeCells xs = object $
-   [ "cells" .= Array (V.fromList (map cellToVal xs)) ]
+  ["cells" .= Array (V.fromList (map cellToVal xs))]
   ++ boilerplate
 
 cellToVal :: Cell [T.Text] -> Value
 cellToVal (Code i o) = object $
-  [ "cell_type" .= String "code",
-    "execution_count" .= Null,
-    "metadata" .= object [ "collapsed" .= Bool False ],
-    "source" .= arrayFromTxt i,
-    "outputs" .= Array
-        (V.fromList (
-           [ object ["text" .= arrayFromTxt o,
-             "metadata" .= object [],
-             "output_type" .= String "display_data" ]
-          | _ <- take 1 o])) ]
-
+  [ "cell_type" .= String "code"
+  , "execution_count" .= Null
+  , "metadata" .= object ["collapsed" .= Bool False]
+  , "source" .= arrayFromTxt i
+  , "outputs" .= Array
+                   (V.fromList
+                      ([object
+                          [ "text" .= arrayFromTxt o
+                          , "metadata" .= object []
+                          , "output_type" .= String "display_data"
+                          ] | _ <- take 1 o]))
+  ]
 cellToVal (Markdown txt) = object $
-  [ "cell_type" .= String "markdown",
-    "metadata" .= object [ "hidden" .= Bool False ],
-    "source" .= arrayFromTxt txt ]
+  [ "cell_type" .= String "markdown"
+  , "metadata" .= object ["hidden" .= Bool False]
+  , "source" .= arrayFromTxt txt
+  ]
 
 -- | arrayFromTxt makes a JSON array of string s
 arrayFromTxt :: [T.Text] -> Value
@@ -76,44 +81,41 @@ arrayFromTxt i = Array (V.fromList $ map stringify i)
   where
     stringify = String . T.toStrict . flip T.snoc '\n'
 
--- | ihaskell needs this boilerplate at the upper level to interpret the
--- json describing cells and output correctly.
+-- | ihaskell needs this boilerplate at the upper level to interpret the json describing cells and
+-- output correctly.
 boilerplate :: [(TS.Text, Value)]
 boilerplate =
-  [ "metadata" .= object [ kernelspec, lang ]
-  , "nbformat" .= Number 4
-  , "nbformat_minor" .= Number 0
-  ]
+  ["metadata" .= object [kernelspec, lang], "nbformat" .= Number 4, "nbformat_minor" .= Number 0]
   where
-    kernelspec = "kernelspec" .= object [
-        "display_name" .= String "Haskell"
+    kernelspec = "kernelspec" .= object
+                                   [ "display_name" .= String "Haskell"
                                    , "language" .= String "haskell"
                                    , "name" .= String "haskell"
                                    ]
-    lang = "language_info" .= object [
-        "name" .= String "haskell"
-      , "version" .= String VERSION_ghc
-      ]
+    lang = "language_info" .= object ["name" .= String "haskell", "version" .= String VERSION_ghc]
 
 groupClassified :: [CellLine T.Text] -> [Cell [T.Text]]
-groupClassified (CodeLine a : x)
-    | (c,x) <- span isCode x,
-      (_,x) <- span isEmptyMD x,
-      (o,x) <- span isOutput x = Code (a : map untag c) (map untag o) : groupClassified x
-groupClassified (MarkdownLine a : x)
-    | (m,x) <- span isMD x = Markdown (a: map untag m) : groupClassified x
-groupClassified (OutputLine a : x ) = Markdown [a] : groupClassified x
+groupClassified (CodeLine a:x)
+  | (c, x) <- span isCode x,
+    (_, x) <- span isEmptyMD x,
+    (o, x) <- span isOutput x
+  = Code (a : map untag c) (map untag o) : groupClassified x
+groupClassified (MarkdownLine a:x)
+  | (m, x) <- span isMD x = Markdown (a : map untag m) : groupClassified x
+groupClassified (OutputLine a:x) = Markdown [a] : groupClassified x
 groupClassified [] = []
 
 classifyLines :: LhsStyle T.Text -> [T.Text] -> [CellLine T.Text]
-classifyLines sty@(LhsStyle c o _ _ _ _) (l:ls) = case (sp c, sp o) of
+classifyLines sty@(LhsStyle c o _ _ _ _) (l:ls) =
+  case (sp c, sp o) of
     (Just a, Nothing)  -> CodeLine a : classifyLines sty ls
     (Nothing, Just a)  -> OutputLine a : classifyLines sty ls
-    (Nothing,Nothing) -> MarkdownLine l : classifyLines sty ls
+    (Nothing, Nothing) -> MarkdownLine l : classifyLines sty ls
     _                  -> error "IHaskell.Convert.classifyLines"
   where
     sp x = T.stripPrefix (dropSpace x) (dropSpace l) `mplus` blankCodeLine x
-    blankCodeLine x = if T.strip x == T.strip l then Just "" else Nothing
+    blankCodeLine x = if T.strip x == T.strip l
+                        then Just ""
+                        else Nothing
     dropSpace = T.dropWhile isSpace
 classifyLines _ [] = []
-

src/IHaskell/Display.hs

 {-# LANGUAGE NoImplicitPrelude, OverloadedStrings, FlexibleInstances #-}
 
--- | If you are interested in the IHaskell library for the purpose of
--- augmenting the IHaskell notebook or writing your own display mechanisms
--- and widgets, this module contains all functions you need. 
+-- | If you are interested in the IHaskell library for the purpose of augmenting the IHaskell
+-- notebook or writing your own display mechanisms and widgets, this module contains all functions
+-- you need.
 --
--- In order to create a display mechanism for a particular data type, write
--- a module named (for example) @IHaskell.Display.YourThing@ in a package named @ihaskell-yourThing@.
--- (Note the capitalization - it's important!) Then, in that module, add an
--- instance of @IHaskellDisplay@ for your data type. Similarly, to create
--- a widget, add an instance of @IHaskellWidget@. 
+-- In order to create a display mechanism for a particular data type, write a module named (for
+-- example) @IHaskell.Display.YourThing@ in a package named @ihaskell-yourThing@. (Note the
+-- capitalization - it's important!) Then, in that module, add an instance of @IHaskellDisplay@ for
+-- your data type. Similarly, to create a widget, add an instance of @IHaskellWidget@.
 --
--- An example of creating a display is provided in the <http://gibiansky.github.io/IHaskell/demo.html demo notebook>.
+-- An example of creating a display is provided in the
+-- <http://gibiansky.github.io/IHaskell/demo.html demo notebook>.
 --
 module IHaskell.Display (
     -- * Rich display and interactive display typeclasses and types
@@ -23,11 +23,21 @@ module IHaskell.Display (
     printDisplay,
 
     -- * Constructors for displays
-  plain, html, png, jpg, svg, latex, javascript, many,
+    plain,
+    html,
+    png,
+    jpg,
+    svg,
+    latex,
+    javascript,
+    many,
 
     -- ** Image and data encoding functions
-  Width, Height, Base64(..),
-  encode64, base64,
+    Width,
+    Height,
+    Base64(..),
+    encode64,
+    base64,
 
     -- ** Utilities
     switchToTmpDir,
@@ -45,7 +55,7 @@ import Data.String.Utils (rstrip)
 import qualified Data.ByteString.Base64 as Base64
 import qualified Data.ByteString.Char8 as Char
 import           Data.Aeson (Value)
-import System.Directory(getTemporaryDirectory, setCurrentDirectory)
+import           System.Directory (getTemporaryDirectory, setCurrentDirectory)
 
 import           Control.Concurrent.STM.TChan
 import           System.IO.Unsafe (unsafePerformIO)
@@ -61,8 +71,7 @@ type Base64 = Text
 -- > IO [Display]
 -- > IO (IO Display)
 --
--- be run the IO and get rendered (if the frontend allows it) in the pretty
--- form.
+-- be run the IO and get rendered (if the frontend allows it) in the pretty form.
 instance IHaskellDisplay a => IHaskellDisplay (IO a) where
   display = (display =<<)
 
@@ -101,15 +110,15 @@ latex = DisplayData MimeLatex . pack
 javascript :: String -> DisplayData
 javascript = DisplayData MimeJavascript . pack
 
--- | Generate a PNG display of the given width and height. Data must be
--- provided in a Base64 encoded manner, suitable for embedding into HTML.
--- The @base64@ function may be used to encode data into this format.
+-- | Generate a PNG display of the given width and height. Data must be provided in a Base64 encoded
+-- manner, suitable for embedding into HTML. The @base64@ function may be used to encode data into
+-- this format.
 png :: Width -> Height -> Base64 -> DisplayData
 png width height = DisplayData (MimePng width height)
 
--- | Generate a JPG display of the given width and height. Data must be
--- provided in a Base64 encoded manner, suitable for embedding into HTML.
--- The @base64@ function may be used to encode data into this format.
+-- | Generate a JPG display of the given width and height. Data must be provided in a Base64 encoded
+-- manner, suitable for embedding into HTML. The @base64@ function may be used to encode data into
+-- this format.
 jpg :: Width -> Height -> Base64 -> DisplayData
 jpg width height = DisplayData (MimeJpg width height)
 
@@ -121,42 +130,37 @@ encode64 str = base64 $ Char.pack str
 base64 :: ByteString -> Base64
 base64 = decodeUtf8 . Base64.encode
 
--- | For internal use within IHaskell.
--- Serialize displays to a ByteString.
+-- | For internal use within IHaskell. Serialize displays to a ByteString.
 serializeDisplay :: Display -> ByteString
 serializeDisplay = Serialize.encode
 
--- | Items written to this chan will be included in the output sent
--- to the frontend (ultimately the browser), the next time IHaskell
--- has an item to display.
+-- | Items written to this chan will be included in the output sent to the frontend (ultimately the
+-- browser), the next time IHaskell has an item to display.
 {-# NOINLINE displayChan #-}
 displayChan :: TChan Display
 displayChan = unsafePerformIO newTChanIO
 
--- | Take everything that was put into the 'displayChan' at that point
--- out, and make a 'Display' out of it.
+-- | Take everything that was put into the 'displayChan' at that point out, and make a 'Display' out
+-- of it.
 displayFromChan :: IO (Maybe Display)
 displayFromChan =
   Just . many <$> unfoldM (atomically $ tryReadTChan displayChan)
 
--- | This is unfoldM from monad-loops. It repeatedly runs an IO action
--- until it return Nothing, and puts all the Justs in a list.
--- If you find yourself using more functionality from monad-loops, just add
--- the package dependency instead of copying more code from it.
+-- | This is unfoldM from monad-loops. It repeatedly runs an IO action until it return Nothing, and
+-- puts all the Justs in a list. If you find yourself using more functionality from monad-loops,
+-- just add the package dependency instead of copying more code from it.
 unfoldM :: IO (Maybe a) -> IO [a]
-unfoldM f = maybe (return []) (\r -> (r:) <$> unfoldM f) =<< f
+unfoldM f = maybe (return []) (\r -> (r :) <$> unfoldM f) =<< f
 
--- | Write to the display channel. The contents will be displayed in the
--- notebook once the current execution call ends.
+-- | Write to the display channel. The contents will be displayed in the notebook once the current
+-- execution call ends.
 printDisplay :: IHaskellDisplay a => a -> IO ()
 printDisplay disp = display disp >>= atomically . writeTChan displayChan
 
--- | Convenience function for client libraries. Switch to a temporary
--- directory so that any files we create aren't visible. On Unix, this is
--- usually /tmp.
+-- | Convenience function for client libraries. Switch to a temporary directory so that any files we
+-- create aren't visible. On Unix, this is usually /tmp.
 switchToTmpDir = void (try switchDir :: IO (Either SomeException ()))
   where
     switchDir =
       getTemporaryDirectory >>=
       setCurrentDirectory
-

src/IHaskell/Eval/Hoogle.hs

 {-# LANGUAGE NoImplicitPrelude, FlexibleInstances, OverloadedStrings #-}
+
 module IHaskell.Eval.Hoogle (
     search,
     document,
     render,
     OutputFormat(..),
-  HoogleResult
+    HoogleResult,
     ) where
 
 import           ClassyPrelude hiding (last, span, div)
@@ -22,19 +23,13 @@ import qualified Prelude as P
 import           IHaskell.IPython
 
 -- | Types of formats to render output to.
-data OutputFormat
-     = Plain      -- ^ Render to plain text.
+data OutputFormat = Plain      -- ^ Render to plain text.
                   | HTML       -- ^ Render to HTML.
 
-data HoogleResponse = HoogleResponse {
-    location :: String,
-    self :: String,
-    docs :: String
-  }
+data HoogleResponse = HoogleResponse { location :: String, self :: String, docs :: String }
   deriving (Eq, Show)
 
-data HoogleResult
-     = SearchResult HoogleResponse
+data HoogleResult = SearchResult HoogleResponse
                   | DocResult HoogleResponse
                   | NoResult String
   deriving Show
@@ -48,23 +43,21 @@ instance FromJSON [HoogleResponse] where
 
 instance FromJSON HoogleResponse where
   parseJSON (Object obj) =
-    HoogleResponse      <$>
-    obj .: "location" <*>
-    obj .: "self"     <*>
-    obj .: "docs"
+    HoogleResponse <$> obj .: "location" <*> obj .: "self" <*> obj .: "docs"
 
   parseJSON _ = fail "Expected object with fields: location, self, docs"
 
--- | Query Hoogle for the given string.
--- This searches Hoogle using the internet. It returns either an error
--- message or the successful JSON result.
+-- | Query Hoogle for the given string. This searches Hoogle using the internet. It returns either
+-- an error message or the successful JSON result.
 query :: String -> IO (Either String String)
 query str = do
   request <- parseUrl $ queryUrl $ urlEncode str
   response <- try $ withManager tlsManagerSettings $ httpLbs request
-  return $ case response of
+  return $
+    case response of
       Left err   -> Left $ show (err :: SomeException)
       Right resp -> Right $ Char.unpack $ responseBody resp
+
   where
     queryUrl :: String -> String
     queryUrl = printf "https://www.haskell.org/hoogle/?hoogle=%s&mode=json"
@@ -78,27 +71,27 @@ urlEncode (ch:t)
   | otherwise = escape (P.fromEnum ch) (urlEncode t)
   where
     escape :: Int -> String -> String
-     escape b rs = '%':showH (b `P.div` 16) (showH (b `mod` 16) rs)
+    escape b rs = '%' : showH (b `P.div` 16) (showH (b `mod` 16) rs)
 
     showH :: Int -> String -> String
     showH x xs
       | x <= 9 = toEnum (o_0 + x) : xs
-       | otherwise = toEnum (o_A + (x-10)) : xs
+      | otherwise = toEnum (o_A + (x - 10)) : xs
       where
         o_0 = P.fromEnum '0'
         o_A = P.fromEnum 'A'
 
     eightBs :: [Int] -> Int -> [Int]
     eightBs acc x
-      | x <= 0xff = (x:acc)
+      | x <= 255 = x : acc
       | otherwise = eightBs ((x `mod` 256) : acc) (x `P.div` 256)
 
--- | Search for a query on Hoogle.
--- Return all search results.
+-- | Search for a query on Hoogle. Return all search results.
 search :: String -> IO [HoogleResult]
 search string = do
   response <- query string
-  return $ case response of
+  return $
+    case response of
       Left err -> [NoResult err]
       Right json ->
         case eitherDecode $ Char.pack json of
@@ -108,16 +101,17 @@ search string = do
               []  -> [NoResult "no matching identifiers found."]
               res -> res
 
--- | Look up an identifier on Hoogle.
--- Return documentation for that identifier. If there are many
+-- | Look up an identifier on Hoogle. Return documentation for that identifier. If there are many
 -- identifiers, include documentation for all of them.
 document :: String -> IO [HoogleResult]
 document string = do
   matchingResults <- filter matches <$> search string
   let results = map toDocResult matchingResults
-  return $ case results of
+  return $
+    case results of
       []  -> [NoResult "no matching identifiers found."]
       res -> res
+
   where
     matches (SearchResult resp) =
       case split " " $ self resp of
@@ -134,21 +128,14 @@ render HTML  = renderHtml
 
 -- | Render a Hoogle result to plain text.
 renderPlain :: HoogleResult -> String
-
 renderPlain (NoResult res) =
   "No response available: " ++ res
 
 renderPlain (SearchResult resp) =
-  printf "%s\nURL: %s\n%s"
-  (self resp)
-  (location resp)
-  (docs resp)
+  printf "%s\nURL: %s\n%s" (self resp) (location resp) (docs resp)
 
 renderPlain (DocResult resp) =
-  printf "%s\nURL: %s\n%s"
-  (self resp)
-  (location resp)
-  (docs resp)
+  printf "%s\nURL: %s\n%s" (self resp) (location resp) (docs resp)
 
 -- | Render a Hoogle result to HTML.
 renderHtml :: HoogleResult -> String
@@ -167,37 +154,37 @@ renderHtml (SearchResult resp) =
 
 renderSelf :: String -> String -> String
 renderSelf string loc
-  | startswith "package" string
-    = pkg ++ " " ++ span "hoogle-package" (link loc $ extractPackage string)
+  | startswith "package" string =
+      pkg ++ " " ++ span "hoogle-package" (link loc $ extractPackage string)
 
-  | startswith "module" string
-    = let package = extractPackageName loc in
-        mod ++ " " ++
+  | startswith "module" string =
+      let package = extractPackageName loc
+      in mod ++ " " ++
                 span "hoogle-module" (link loc $ extractModule string) ++
                 packageSub package
 
-  | startswith "class" string
-    = let package = extractPackageName loc in
-        cls ++ " " ++
+  | startswith "class" string =
+      let package = extractPackageName loc
+      in cls ++ " " ++
                 span "hoogle-class" (link loc $ extractClass string) ++
                 packageSub package
 
-  | startswith "data" string
-    = let package = extractPackageName loc in
-        dat ++ " " ++
+  | startswith "data" string =
+      let package = extractPackageName loc
+      in dat ++ " " ++
                 span "hoogle-class" (link loc $ extractData string) ++
                 packageSub package
 
-  | otherwise
-    = let [name, args] = split "::" string
+  | otherwise =
+      let [name, args] = split "::" string
           package = extractPackageName loc
-          modname = extractModuleName loc in
-        span "hoogle-name" (unicodeReplace $
+          modname = extractModuleName loc
+      in span "hoogle-name"
+           (unicodeReplace $
               link loc (strip name) ++
               " :: " ++
               strip args)
          ++ packageAndModuleSub package modname
-
   where
     extractPackage = strip . replace "package" ""
     extractModule = strip . replace "module" ""
@@ -239,8 +226,7 @@ renderDocs doc =
                          if isCode lines
                            then div "hoogle-code" $ unlines $ nonull lines
                            else div "hoogle-text" $ unlines $ nonull lines
-      in
-    div "hoogle-doc" $ unlines $ map makeBlock groups
+  in div "hoogle-doc" $ unlines $ map makeBlock groups
 
 extractPackageName :: String -> Maybe String
 extractPackageName link = do

src/IHaskell/Eval/Info.hs

 {-# LANGUAGE NoImplicitPrelude, OverloadedStrings #-}
-{- | Description : Inspect type and function information and documentation.
--}
-module IHaskell.Eval.Info (
-  info
-  ) where
+
+{- | Description : Inspect type and function information and documentation.  -}
+module IHaskell.Eval.Info (info) where
 
 import           ClassyPrelude hiding (liftIO)
 

src/IHaskell/Eval/Lint.hs

 {-# LANGUAGE NoImplicitPrelude, QuasiQuotes, ViewPatterns #-}
-module IHaskell.Eval.Lint ( 
-  lint
-  ) where
+
+module IHaskell.Eval.Lint (lint) where
 
 import           Data.String.Utils (replace, startswith, strip, split)
 import           Prelude (head, tail, last)
@@ -32,13 +31,13 @@ import IHaskell.Eval.Parser hiding (line)
 
 type ExtsModule = SrcExts.Module SrcSpanInfo
 
-data LintSuggestion
-  = Suggest {
-    line :: LineNumber,
-    found :: String,
-    whyNot :: String,
-    severity :: Severity,
-    suggestion :: String
+data LintSuggestion =
+       Suggest
+         { line :: LineNumber
+         , found :: String
+         , whyNot :: String
+         , severity :: Severity
+         , suggestion :: String
          }
   deriving (Eq, Show)
 
@@ -51,8 +50,8 @@ hlintSettings = unsafePerformIO newEmptyMVar
 lintIdent :: String
 lintIdent = "lintIdentAEjlkQeh"
 
--- | Given parsed code chunks, perform linting and output a displayable
--- report on linting warnings and errors.
+-- | Given parsed code chunks, perform linting and output a displayable report on linting warnings
+-- and errors.
 lint :: [Located CodeBlock] -> IO Display
 lint blocks = do
   -- Initialize hlint settings
@@ -66,26 +65,25 @@ lint blocks = do
 
   -- create 'suggestions'
   let modules = mapMaybe (createModule mode) blocks
-      ideas = applyHints classify hint (map (\m->(m,[])) modules)
+      ideas = applyHints classify hint (map (\m -> (m, [])) modules)
       suggestions = mapMaybe showIdea ideas
 
   return $ Display $
     if null suggestions
       then []
-    else 
-      [plain $ concatMap plainSuggestion suggestions,
-       html $ htmlSuggestions suggestions]
+      else [plain $ concatMap plainSuggestion suggestions, html $ htmlSuggestions suggestions]
 
 showIdea :: Idea -> Maybe LintSuggestion
 showIdea idea =
   case ideaTo idea of
     Nothing -> Nothing
-    Just whyNot -> Just Suggest {
-      line = srcSpanStartLine $ ideaSpan idea,
-      found = showSuggestion $ ideaFrom idea,
-      whyNot = showSuggestion whyNot,
-      severity = ideaSeverity idea,
-      suggestion = ideaHint idea
+    Just whyNot -> Just
+                     Suggest
+                       { line = srcSpanStartLine $ ideaSpan idea
+                       , found = showSuggestion $ ideaFrom idea
+                       , whyNot = showSuggestion whyNot
+                       , severity = ideaSeverity idea
+                       , suggestion = ideaHint idea
                        }
 
 createModule :: ParseMode -> Located CodeBlock -> Maybe ExtsModule
@@ -111,12 +109,12 @@ createModule mode (Located line block) =
     unparse _ = Nothing
 
     srcSpan :: SrcSpan
-    srcSpan = SrcSpan {
-      srcSpanFilename = "<interactive>",
-      srcSpanStartLine = line,
-      srcSpanStartColumn = 0,
-      srcSpanEndLine = line + length (lines blockStr),
-      srcSpanEndColumn = length $ last $ lines blockStr
+    srcSpan = SrcSpan
+      { srcSpanFilename = "<interactive>"
+      , srcSpanStartLine = line
+      , srcSpanStartColumn = 0
+      , srcSpanEndLine = line + length (lines blockStr)
+      , srcSpanEndColumn = length $ last $ lines blockStr
       }
 
     loc :: SrcSpanInfo
@@ -135,7 +133,8 @@ createModule mode (Located line block) =
     exprToModule exp = moduleWithDecls <$> SpliceDecl loc <$> parseExpWithMode mode exp
 
     stmtToModule :: String -> ParseResult ExtsModule
-    stmtToModule stmtStr = case parseStmtWithMode mode stmtStr of
+    stmtToModule stmtStr =
+      case parseStmtWithMode mode stmtStr of
         ParseOk stmt    -> ParseOk mod
         ParseFailed a b -> ParseFailed a b
       where
@@ -158,10 +157,7 @@ createModule mode (Located line block) =
 
 plainSuggestion :: LintSuggestion -> String
 plainSuggestion suggest =
-  printf "Line %d: %s\nFound:\n%s\nWhy not:\n%s"
-    (line suggest)
-    (suggestion suggest)
-    (found suggest)
+  printf "Line %d: %s\nFound:\n%s\nWhy not:\n%s" (line suggest) (suggestion suggest) (found suggest)
     (whyNot suggest)
 
 htmlSuggestions :: [LintSuggestion] -> String
@@ -169,18 +165,17 @@ htmlSuggestions = concatMap toHtml
   where
     toHtml :: LintSuggestion -> String
     toHtml suggest = concat
-      [
-      named $ suggestion suggest,
-      floating "left" $ style severityClass "Found:" ++
+                       [ named $ suggestion suggest
+                       , floating "left" $ style severityClass "Found:" ++
                                            -- Things that look like this get highlighted.
-             styleId "highlight-code" "haskell" (found suggest),
-      floating "left" $ style severityClass "Why Not:" ++
+                                           styleId "highlight-code" "haskell" (found suggest)
+                       , floating "left" $ style severityClass "Why Not:" ++
                                            -- Things that look like this get highlighted.
                                            styleId "highlight-code" "haskell" (whyNot suggest)
                        ]
-
       where
-        severityClass = case severity suggest of
+        severityClass =
+          case severity suggest of
             Error -> "error"
             Warning -> "warning"
 
@@ -199,7 +194,6 @@ htmlSuggestions = concatMap toHtml
     floating :: String -> String -> String
     floating dir thing = [i| <div class="suggestion-row" style="float: ${dir};">${thing}</div> |]
 
-
 showSuggestion :: String -> String
 showSuggestion = remove lintIdent . dropDo
   where
@@ -214,18 +208,14 @@ showSuggestion = remove lintIdent .  dropDo
         else string
 
     clean :: [String] -> [String]
-    -- If the first line starts with a `do`...
-    -- Note that hlint always indents by two spaces in its output.
-    clean ((stripPrefix "  do " -> Just a) : as) =
+    -- If the first line starts with a `do`... Note that hlint always indents by two spaces in its
+    -- output.
+    clean ((stripPrefix "  do " -> Just a):as) =
       -- Take all indented lines and unindent them.
-        let unindented = catMaybes
-                $ takeWhile isJust
-                $ map (stripPrefix "     ") as
-            fullDo = a:unindented
+      let unindented = catMaybes $ takeWhile isJust $ map (stripPrefix "     ") as
+          fullDo = a : unindented
           afterDo = drop (length unindented) as
-        in 
-          -- 
-          fullDo ++ clean afterDo
+      in fullDo ++ clean afterDo
 
     -- Ignore other list elements - just proceed onwards.
     clean (x:xs) = x : clean xs

src/IHaskell/Eval/ParseShell.hs

-
 -- | This module splits a shell command line into a list of strings,
 --   one for each command / filename
 module IHaskell.Eval.ParseShell (parseShell) where
@@ -20,9 +19,10 @@ manyTill p end = scan
     scan = end <|> do
              x <- p
              xs <- scan
-      return $ x:xs
+             return $ x : xs
 
-manyTill1 p end = do x <- p 
+manyTill1 p end = do
+  x <- p
   xs <- manyTill p end
   return $ x : xs
 
@@ -37,7 +37,8 @@ quotedString = do
   (manyTill anyChar (unescapedChar quote) <* quote) <?> "unexpected in quoted String "
 
 unquotedString = manyTill1 anyChar end
-  where end = unescapedChar space 
+  where
+    end = unescapedChar space
           <|> (lookAhead eol >> return [])
 
 word = quotedString <|> unquotedString <?> "word"

src/IHaskell/Flags.hs

 {-# LANGUAGE NoImplicitPrelude, DeriveFunctor #-}
+
 module IHaskell.Flags (
     IHaskellMode(..),
     Argument(..),
@@ -16,8 +17,7 @@ import           System.Console.CmdArgs.Text
 import           Data.List (findIndex)
 import           IHaskell.Types
 
--- Command line arguments to IHaskell.  A set of aruments is annotated with
--- the mode being invoked.
+-- Command line arguments to IHaskell. A set of arguments is annotated with the mode being invoked.
 data Args = Args IHaskellMode [Argument]
   deriving Show
 
@@ -33,7 +33,9 @@ data Argument = ConfFile String     -- ^ A file with commands to load at startup
               | ConvertLhsStyle (LhsStyle String)
   deriving (Eq, Show)
 
-data LhsStyle string = LhsStyle { lhsCodePrefix :: string  -- ^ @>@
+data LhsStyle string =
+       LhsStyle
+         { lhsCodePrefix :: string  -- ^ @>@
          , lhsOutputPrefix :: string  -- ^ @<<@
          , lhsBeginCode :: string  -- ^ @\\begin{code}@
          , lhsEndCode :: string  -- ^ @\\end{code}@
@@ -42,21 +44,18 @@ data LhsStyle string = LhsStyle { lhsCodePrefix :: string  -- ^ @>@
          }
   deriving (Eq, Functor, Show)
 
-
 data NotebookFormat = LhsMarkdown
                     | IpynbFile
   deriving (Eq, Show)
 
 -- Which mode IHaskell is being invoked in.
--- `None` means no mode was specified.
 data IHaskellMode = ShowHelp String
                   | InstallKernelSpec
                   | ConvertLhs
                   | Kernel (Maybe String)
   deriving (Eq, Show)
 
--- | Given a list of command-line arguments, return the IHaskell mode and
--- arguments to process.
+-- | Given a list of command-line arguments, return the IHaskell mode and arguments to process.
 parseFlags :: [String] -> Either String Args
 parseFlags flags =
   let modeIndex = findIndex (`elem` modeFlags) flags
@@ -111,7 +110,8 @@ installKernelSpec =
     [ghcLibFlag, kernelDebugFlag, confFlag, helpFlag]
 
 kernel :: Mode Args
-kernel = mode "kernel" (Args (Kernel Nothing) []) "Invoke the IHaskell kernel." kernelArg [ghcLibFlag, kernelDebugFlag, confFlag]
+kernel = mode "kernel" (Args (Kernel Nothing) []) "Invoke the IHaskell kernel." kernelArg
+           [ghcLibFlag, kernelDebugFlag, confFlag]
   where
     kernelArg = flagArg update "<json-kernel-file>"
     update filename (Args _ flags) = Right $ Args (Kernel $ Just filename) flags
@@ -154,6 +154,7 @@ convert = mode "convert" (Args ConvertLhs []) description unnamedArg convertFlag
 
 lhsStyleBird, lhsStyleTex :: LhsStyle String
 lhsStyleBird = LhsStyle "> " "\n<< " "" "" "" ""
+
 lhsStyleTex = LhsStyle "" "" "\\begin{code}" "\\end{code}" "\\begin{verbatim}" "\\end{verbatim}"
 
 ihaskellArgs :: Mode Args
@@ -161,8 +162,8 @@ ihaskellArgs =
   let descr = "Haskell for Interactive Computing."
       helpStr = showText (Wrap 100) $ helpText [] HelpFormatAll ihaskellArgs
       onlyHelp = [flagHelpSimple (add Help)]
-      noMode = mode "IHaskell" (Args (ShowHelp helpStr) []) descr noArgs onlyHelp in
-    noMode { modeGroupModes = toGroup allModes }
+      noMode = mode "IHaskell" (Args (ShowHelp helpStr) []) descr noArgs onlyHelp
+  in noMode { modeGroupModes = toGroup allModes }
   where
     add flag (Args mode flags) = Args mode $ flag : flags
 

src/IHaskell/IPython.hs

@@ -40,17 +40,20 @@ import qualified GHC.Paths
 import           IHaskell.Types
 import           System.Posix.Signals
 
-
-data KernelSpecOptions = KernelSpecOptions { kernelSpecGhcLibdir :: String           -- ^ GHC libdir.
+data KernelSpecOptions =
+       KernelSpecOptions
+         { kernelSpecGhcLibdir :: String           -- ^ GHC libdir.
          , kernelSpecDebug :: Bool                 -- ^ Spew debugging output?
          , kernelSpecConfFile :: IO (Maybe String) -- ^ Filename of profile JSON file.
          }
 
 defaultKernelSpecOptions :: KernelSpecOptions
-defaultKernelSpecOptions = KernelSpecOptions { kernelSpecGhcLibdir = GHC.Paths.libdir
+defaultKernelSpecOptions = KernelSpecOptions
+  { kernelSpecGhcLibdir = GHC.Paths.libdir
   , kernelSpecDebug = False
   , kernelSpecConfFile = defaultConfFile
   }
+
 -- | The IPython kernel name.
 kernelName :: IsString a => a
 kernelName = "haskell"
@@ -133,6 +136,7 @@ verifyIPythonVersion = do
         Just (1:_) -> oldIPython
         Just (0:_) -> oldIPython
         _          -> badIPython "Detected IPython, but could not parse version number."
+
   where
     badIPython :: Text -> Sh ()
     badIPython message = liftIO $ do
@@ -140,8 +144,8 @@ verifyIPythonVersion = do
       exitFailure
     oldIPython = badIPython "Detected old version of IPython. IHaskell requires 3.0.0 or up."
 
--- | Install an IHaskell kernelspec into the right location.
--- The right location is determined by using `ipython kernelspec install --user`.
+-- | Install an IHaskell kernelspec into the right location. The right location is determined by
+-- using `ipython kernelspec install --user`.
 installKernelspec :: Bool -> KernelSpecOptions -> Sh ()
 installKernelspec replace opts = void $ do
   ihaskellPath <- getIHaskellPath
@@ -155,13 +159,14 @@ installKernelspec replace opts = void $ do
            Just file -> ["--conf", file])
         ++ ["--ghclib", kernelSpecGhcLibdir opts]
 
-  let kernelSpec = KernelSpec { kernelDisplayName = "Haskell"
+  let kernelSpec = KernelSpec
+        { kernelDisplayName = "Haskell"
         , kernelLanguage = kernelName
         , kernelCommand = [ihaskellPath, "kernel", "{connection_file}"] ++ kernelFlags
         }
 
-  -- Create a temporary directory. Use this temporary directory to make a kernelspec
-  -- directory; then, shell out to IPython to install this kernelspec directory.
+  -- Create a temporary directory. Use this temporary directory to make a kernelspec directory; then,
+  -- shell out to IPython to install this kernelspec directory.
   withTmpDir $ \tmp -> do
     let kernelDir = tmp </> kernelName
     let filename = kernelDir </> "kernel.json"
@@ -185,16 +190,14 @@ kernelSpecCreated = do
   let kernelspecs = map T.strip $ lines out
   return $ kernelName `elem` kernelspecs
 
--- | Replace "~" with $HOME if $HOME is defined.
--- Otherwise, do nothing.
+-- | Replace "~" with $HOME if $HOME is defined. Otherwise, do nothing.
 subHome :: String -> IO String
 subHome path = shelly $ do
   home <- unpack <$> fromMaybe "~" <$> get_env "HOME"
   return $ replace "~" home path
 
-
--- | Get the path to an executable. If it doensn't exist, fail with an
--- error message complaining about it.
+-- | Get the path to an executable. If it doensn't exist, fail with an error message complaining
+-- about it.
 path :: Text -> Sh FilePath
 path exe = do
   path <- which $ fromText exe
@@ -229,9 +232,8 @@ getIHaskellPath = do
   if FS.absolute f
     then return $ FS.encodeString f
     else 
-    -- Check whether this is a relative path, or just 'IHaskell' with $PATH
-    -- resolution done by the shell. If it's just 'IHaskell', use the $PATH
-    -- variable to find where IHaskell lives.
+    -- Check whether this is a relative path, or just 'IHaskell' with $PATH resolution done by
+    -- the shell. If it's just 'IHaskell', use the $PATH variable to find where IHaskell lives.
     if FS.filename f == f
       then do
         ihaskellPath <- which "ihaskell"

src/IHaskell/Types.hs

-{-# LANGUAGE NoImplicitPrelude, OverloadedStrings, DeriveDataTypeable, DeriveGeneric #-}
-{-# LANGUAGE ExistentialQuantification #-}
+{-# LANGUAGE NoImplicitPrelude, OverloadedStrings, DeriveDataTypeable, DeriveGeneric, ExistentialQuantification #-}
+
 -- | Description : All message type definitions.
 module IHaskell.Types (
-  Message (..),
-  MessageHeader (..),
+    Message(..),
+    MessageHeader(..),
     MessageType(..),
     Username,
     Metadata(..),
     replyType,
-  ExecutionState (..),
+    ExecutionState(..),
     StreamType(..),
     MimeType(..),
     DisplayData(..),
@@ -16,7 +16,8 @@ module IHaskell.Types (
     ExecuteReplyStatus(..),
     KernelState(..),
     LintStatus(..),
-  Width, Height,
+    Width,
+    Height,
     Display(..),
     defaultKernelState,
     extractPlain,
@@ -40,8 +41,8 @@ import           IHaskell.IPython.Kernel
 
 -- | A class for displayable Haskell types.
 --
--- IHaskell's displaying of results behaves as if these two
--- overlapping/undecidable instances also existed:
+-- IHaskell's displaying of results behaves as if these two overlapping/undecidable instances also
+-- existed:
 -- 
 -- > instance (Show a) => IHaskellDisplay a
 -- > instance Show a where shows _ = id
@@ -50,12 +51,10 @@ 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.
+  -- | Output target name for this widget. The actual input parameter should be ignored.
   targetName :: a -> String
 
-  -- | Called when the comm is opened. Allows additional messages to be sent
-  -- after comm open.
+  -- | Called when the comm is opened. Allows additional messages to be sent after comm open.
   open :: a               -- ^ Widget to open a comm port with.
        -> (Value -> IO ()) -- ^ Way to respond to the message.
        -> IO ()
@@ -89,12 +88,12 @@ instance IHaskellWidget Widget where
 instance Show Widget where
   show _ = "<Widget>"
 
-
--- | Wrapper for ipython-kernel's DisplayData which allows sending multiple
--- results from the same expression.
+-- | Wrapper for ipython-kernel's DisplayData which allows sending multiple results from the same
+-- expression.
 data Display = Display [DisplayData]
              | ManyDisplay [Display]
   deriving (Show, Typeable, Generic)
+
 instance Serialize Display
 
 instance Monoid Display where
@@ -102,13 +101,15 @@ instance Monoid Display where
   ManyDisplay a `mappend` ManyDisplay b = ManyDisplay (a ++ b)
   ManyDisplay a `mappend` b = ManyDisplay (a ++ [b])
   a `mappend` ManyDisplay b = ManyDisplay (a : b)
-    a             `mappend` b             = ManyDisplay [a,b]
+  a `mappend` b = ManyDisplay [a, b]
 
 instance Semigroup Display where
   a <> b = a `mappend` b
 
 -- | All state stored in the kernel between executions.
-data KernelState = KernelState { getExecutionCounter :: Int
+data KernelState =
+       KernelState
+         { getExecutionCounter :: Int
          , getLintStatus :: LintStatus   -- Whether to use hlint, and what arguments to pass it. 
          , useSvg :: Bool
          , useShowErrors :: Bool
@@ -120,7 +121,8 @@ data KernelState = KernelState { getExecutionCounter :: Int
   deriving Show
 
 defaultKernelState :: KernelState
-defaultKernelState = KernelState { getExecutionCounter = 1
+defaultKernelState = KernelState
+  { getExecutionCounter = 1
   , getLintStatus = LintOn
   , useSvg = True
   , useShowErrors = False
@@ -131,10 +133,12 @@ defaultKernelState = KernelState { getExecutionCounter = 1
   }
 
 -- | Kernel options to be set via `:set` and `:option`.
-data KernelOpt = KernelOpt {
-    getOptionName :: [String],                          -- ^ Ways to set this option via `:option`
-    getSetName :: [String],                             -- ^ Ways to set this option via `:set`
-    getUpdateKernelState :: KernelState -> KernelState   -- ^ Function to update the kernel state.
+data KernelOpt =
+       KernelOpt
+         { getOptionName :: [String]                          -- ^ Ways to set this option via `:option`
+         , getSetName :: [String]                             -- ^ Ways to set this option via `:set`
+         , getUpdateKernelState :: KernelState -> KernelState -- ^ Function to update the kernel
+                                                              -- state.
          }
 
 kernelOpts :: [KernelOpt]
@@ -152,23 +156,24 @@ kernelOpts =
   ]
 
 -- | Current HLint status.
-data LintStatus
-     = LintOn
+data LintStatus = LintOn
                 | LintOff
   deriving (Eq, Show)
 
-data CommInfo = CommInfo Widget UUID String deriving Show
+data CommInfo = CommInfo Widget UUID String
+  deriving Show
 
 -- | Output of evaluation.
 data EvaluationResult =
                       -- | An intermediate result which communicates what has been printed thus
                       -- far.
-  IntermediateResult {
-    outputs :: Display      -- ^ Display outputs.
+                        IntermediateResult
+                          { outputs :: Display      -- ^ Display outputs.
                           }
-  | FinalResult {
-    outputs :: Display,       -- ^ Display outputs.
-    pagerOut :: String,       -- ^ Text to display in the IPython pager.
-    startComms :: [CommInfo]  -- ^ Comms to start.
+                      |
+                        FinalResult
+                          { outputs :: Display        -- ^ Display outputs.
+                          , pagerOut :: String        -- ^ Text to display in the IPython pager.
+                          , startComms :: [CommInfo]  -- ^ Comms to start.
                           }
   deriving Show

verify_formatting.py

+#!/usr/bin/env python3
+
+from __future__ import print_function
+
+import sys
+import os
+import subprocess
+
+
+def hindent(contents):
+    with open(".tmp3", "w") as f:
+        f.write(contents)
+    with open(".tmp3", "r") as f:
+        output = subprocess.check_output(["hindent", "--style", "gibiansky"],
+                                         stdin=f)
+    return output.decode('utf-8')
+
+
+def diff(src1, src2):
+    # Ignore trailing newlines
+    if src1[-1] == "\n":
+        src1 = src1[:-1]
+    if src2[-1] == "\n":
+        src2 = src2[:-1]
+
+    with open(".tmp1", "w") as f1:
+        f1.write(src1)
+
+    with open(".tmp2", "w") as f2:
+        f2.write(src2)
+
+    try:
+        output = subprocess.check_output(["diff", ".tmp1", ".tmp2"])
+        return output.decode('utf-8')
+    except subprocess.CalledProcessError as e:
+        return e.output.decode('utf-8')
+
+# Verify that we're in the right directory
+try:
+    open("ihaskell.cabal", "r").close()
+except:
+    print(sys.argv[0], "must be run from the ihaskell directory",
+          file=sys.stderr)
+
+# Find all the source files
+sources = []
+for root, dirnames, filenames in os.walk("src"):
+    for filename in filenames:
+        if filename.endswith(".hs"):
+            sources.append(os.path.join(root, filename))
+
+
+hindent_outputs = {}
+for source_file in sources:
+    print("Formatting file", source_file)
+    with open(source_file, "r") as f:
+        original_source = f.read()
+    formatted_source = hindent(original_source)
+
+    hindent_outputs[source_file] = (original_source, formatted_source)
+
+diffs = {filename: diff(original, formatted)
+         for (filename, (original, formatted)) in hindent_outputs.items()}
+
+incorrect_formatting = False
+for filename, diff in diffs.items():
+    if diff:
+        incorrect_formatting = True
+        print('Incorrect formatting in', filename)
+        print('=' * 10)
+        print(diff)
+
+if incorrect_formatting:
+    sys.exit(1)