diff --git a/src-brittany/Main.hs b/src-brittany/Main.hs
index 4699346..9ddd5a6 100644
--- a/src-brittany/Main.hs
+++ b/src-brittany/Main.hs
@@ -46,36 +46,40 @@ main = mainFromCmdParserWithHelpDesc mainCmdParser
 mainCmdParser :: CommandDesc () -> CmdParser Identity (IO ()) ()
 mainCmdParser helpDesc = do
   addCmdSynopsis "haskell source pretty printer"
-  addCmdHelp $ PP.vcat $ List.intersperse (PP.text "")
-    [ parDoc $ "Transforms one haskell module by reformatting"
-            ++ " (parts of) the source code (while preserving the"
-            ++ " parts not transformed)."
-    , parDoc $ "Based on ghc-exactprint, thus (theoretically) supporting all"
-            ++ " that ghc does."
-    , parDoc $ "This is an early, experimental release."
-            ++ " Only type-signatures and function-bindings are transformed."
-            ++ " There is a check in place, but no warranties that the output"
-            ++ " is valid haskell."
+  addCmdHelp $ PP.vcat $ List.intersperse
+    (PP.text "")
+    [ parDoc
+      $  "Transforms one haskell module by reformatting"
+      ++ " (parts of) the source code (while preserving the"
+      ++ " parts not transformed)."
+    , parDoc $ "Based on ghc-exactprint, thus (theoretically) supporting all" ++ " that ghc does."
+    , parDoc
+      $  "This is an early, experimental release."
+      ++ " Only type-signatures and function-bindings are transformed."
+      ++ " There is a check in place, but no warranties that the output"
+      ++ " is valid haskell."
     , parDoc $ "There is NO WARRANTY, to the extent permitted by law."
     , parDoc $ "See https://github.com/lspitzner/brittany"
-    , parDoc $ "Please report bugs at"
-            ++ " https://github.com/lspitzner/brittany/issues"
+    , parDoc $ "Please report bugs at" ++ " https://github.com/lspitzner/brittany/issues"
     ]
   -- addCmd "debugArgs" $ do
   addHelpCommand helpDesc
   -- addButcherDebugCommand
   reorderStart
-  printHelp <- addSimpleBoolFlag "" ["help"] mempty
-  printVersion <- addSimpleBoolFlag "" ["version"] mempty
-  inputPaths <- addFlagStringParams "i" ["input"] "PATH" (flagHelpStr "path to input haskell source file")
-  outputPaths <- addFlagStringParams "o" ["output"] "PATH" (flagHelpStr "output file path")
-  configPaths <- addFlagStringParams "" ["config-file"] "PATH" (flagHelpStr "path to config file") -- TODO: allow default on addFlagStringParam ?
-  cmdlineConfig <- configParser
-  suppressOutput <- addSimpleBoolFlag "" ["suppress-output"] (flagHelp $ parDoc "suppress the regular output, i.e. the transformed haskell source")
+  printHelp      <- addSimpleBoolFlag "" ["help"] mempty
+  printVersion   <- addSimpleBoolFlag "" ["version"] mempty
+  inputPaths     <- addFlagStringParams "i" ["input"] "PATH" (flagHelpStr "path to input haskell source file")
+  outputPaths    <- addFlagStringParams "o" ["output"] "PATH" (flagHelpStr "output file path")
+  configPaths    <- addFlagStringParams "" ["config-file"] "PATH" (flagHelpStr "path to config file") -- TODO: allow default on addFlagStringParam ?
+  cmdlineConfig  <- configParser
+  suppressOutput <- addSimpleBoolFlag
+    ""
+    ["suppress-output"]
+    (flagHelp $ parDoc "suppress the regular output, i.e. the transformed haskell source")
   _verbosity <- addSimpleCountFlag "v" ["verbose"] (flagHelp $ parDoc "[currently without effect; TODO]")
   reorderStop
   inputParam <- addStringParamOpt "PATH" (paramHelpStr "path to input haskell source file")
-  desc <- peekCmdDesc
+  desc       <- peekCmdDesc
   addCmdImpl $ void $ do
     when printVersion $ do
       liftIO $ do
@@ -90,31 +94,24 @@ mainCmdParser helpDesc = do
       [] -> do
         return Nothing
       [x] -> return $ Just x
-      _ -> do
+      _   -> do
         liftIO $ putStrErrLn $ "more than one input, aborting"
         System.Exit.exitWith (System.Exit.ExitFailure 50)
     outputPath <- case outputPaths of
       [] -> do
         return Nothing
       [x] -> return $ Just x
-      _ -> do
+      _   -> do
         liftIO $ putStrErrLn $ "more than one output, aborting"
         System.Exit.exitWith (System.Exit.ExitFailure 50)
     config <- runMaybeT (readConfigs cmdlineConfig configPaths) >>= \case
       Nothing -> System.Exit.exitWith (System.Exit.ExitFailure 50)
-      Just x -> return x
+      Just x  -> return x
     when (confUnpack $ _dconf_dump_config $ _conf_debug $ config) $ do
       trace (showConfigYaml config) $ return ()
-    let ghcOptions = config
-                   & _conf_forward
-                   & _options_ghc
-                   & runIdentity
+    let ghcOptions = config & _conf_forward & _options_ghc & runIdentity
     liftIO $ do
-      let cppMode = config
-                  & _conf_preprocessor
-                  & _ppconf_CPPMode
-                  & runIdentity
-                  & Semigroup.getLast
+      let cppMode = config & _conf_preprocessor & _ppconf_CPPMode & runIdentity & Semigroup.getLast
       -- the flag will do the following: insert a marker string
       -- ("-- BRITTANY_INCLUDE_HACK ") right before any lines starting with
       -- "#include" before processing (parsing) input; and remove that marker
@@ -132,8 +129,7 @@ mainCmdParser helpDesc = do
                   ++ " brittany cannot check that its output is syntactically"
                   ++ " valid in its presence."
                 return $ Right True
-              CPPModeNowarn ->
-                return $ Right True
+              CPPModeNowarn -> return $ Right True
             else return $ Right False
       parseResult <- case inputPathM of
         Nothing -> do
@@ -170,12 +166,10 @@ mainCmdParser helpDesc = do
               customErrOrder LayoutErrorUnusedComment{} = 2
               customErrOrder LayoutErrorUnknownNode{}   = 3
           when (not $ null errsWarns) $ do
-            let groupedErrsWarns = Data.List.Extra.groupOn customErrOrder
-                                 $ List.sortOn customErrOrder
-                                 $ errsWarns
+            let groupedErrsWarns = Data.List.Extra.groupOn customErrOrder $ List.sortOn customErrOrder $ errsWarns
             groupedErrsWarns `forM_` \case
               (LayoutErrorOutputCheck{}:_) -> do
-                putStrErrLn $ "ERROR: brittany pretty printer returned syntactically invalid result."
+                putStrErrLn $ "ERROR: brittany pretty printer" ++ " returned syntactically invalid result."
               uns@(LayoutErrorUnknownNode{}:_) -> do
                 putStrErrLn $ "ERROR: encountered unknown syntactical constructs:"
                 uns `forM_` \case
@@ -188,49 +182,44 @@ mainCmdParser helpDesc = do
                 putStrErrLn $ "WARNINGS:"
                 warns `forM_` \case
                   LayoutWarning str -> putStrErrLn str
-                  _ -> error "cannot happen (TM)"
+                  _                 -> error "cannot happen (TM)"
               unused@(LayoutErrorUnusedComment{}:_) -> do
-                putStrErrLn $ "Error: detected unprocessed comments. the transformation "
-                        ++ "output will most likely not contain certain of the comments "
-                        ++ "present in the input haskell source file."
+                putStrErrLn
+                  $  "Error: detected unprocessed comments."
+                  ++ " The transformation output will most likely"
+                  ++ " not contain certain of the comments"
+                  ++ " present in the input haskell source file."
                 putStrErrLn $ "Affected are the following comments:"
                 unused `forM_` \case
                   LayoutErrorUnusedComment str -> putStrErrLn str
-                  _ -> error "cannot happen (TM)"
+                  _                            -> error "cannot happen (TM)"
               [] -> error "cannot happen"
           -- TODO: don't output anything when there are errors unless user
           -- adds some override?
-          let hasErrors = case config
-                               & _conf_errorHandling
-                               & _econf_Werror
-                               & confUnpack of
+          let hasErrors = case config & _conf_errorHandling & _econf_Werror & confUnpack of
                 False -> 0 < maximum (-1 : fmap customErrOrder errsWarns)
                 True  -> not $ null errsWarns
-              outputOnErrs = config
-                           & _conf_errorHandling
-                           & _econf_produceOutputOnErrors
-                           & confUnpack
-          let shouldOutput = not suppressOutput
-                          && (not hasErrors || outputOnErrs)
+              outputOnErrs = config & _conf_errorHandling & _econf_produceOutputOnErrors & confUnpack
+              shouldOutput = not suppressOutput && (not hasErrors || outputOnErrs)
 
           when shouldOutput $ addTraceSep (_conf_debug config) $ case outputPath of
-            Nothing -> TextL.IO.putStr     $ outLText
-            Just p -> TextL.IO.writeFile p $ outLText
+            Nothing -> TextL.IO.putStr $ outLText
+            Just p  -> TextL.IO.writeFile p $ outLText
 
-          when hasErrors $
-            System.Exit.exitWith (System.Exit.ExitFailure 70)
-  where
-    addTraceSep conf = if or
-        [ confUnpack $ _dconf_dump_annotations conf
-        , confUnpack $ _dconf_dump_ast_unknown conf
-        , confUnpack $ _dconf_dump_ast_full conf
-        , confUnpack $ _dconf_dump_bridoc_raw conf
-        , confUnpack $ _dconf_dump_bridoc_simpl_alt conf
-        , confUnpack $ _dconf_dump_bridoc_simpl_floating conf
-        , confUnpack $ _dconf_dump_bridoc_simpl_columns conf
-        , confUnpack $ _dconf_dump_bridoc_simpl_indent conf
-        , confUnpack $ _dconf_dump_bridoc_final conf
-        ]
+          when hasErrors $ System.Exit.exitWith (System.Exit.ExitFailure 70)
+ where
+  addTraceSep conf =
+    if or
+         [ confUnpack $ _dconf_dump_annotations conf
+         , confUnpack $ _dconf_dump_ast_unknown conf
+         , confUnpack $ _dconf_dump_ast_full conf
+         , confUnpack $ _dconf_dump_bridoc_raw conf
+         , confUnpack $ _dconf_dump_bridoc_simpl_alt conf
+         , confUnpack $ _dconf_dump_bridoc_simpl_floating conf
+         , confUnpack $ _dconf_dump_bridoc_simpl_columns conf
+         , confUnpack $ _dconf_dump_bridoc_simpl_indent conf
+         , confUnpack $ _dconf_dump_bridoc_final conf
+         ]
       then trace "----"
       else id
 
@@ -240,13 +229,11 @@ readConfigs cmdlineConfig configPaths = do
   userBritPath <- liftIO $ Directory.getAppUserDataDirectory "brittany"
   let defUserConfigPath = userBritPath FilePath.</> "config.yaml"
   merged <- case configPaths of
-    []    -> do
+    [] -> do
       liftIO $ Directory.createDirectoryIfMissing False userBritPath
       return cmdlineConfig
         >>= readMergePersConfig defLocalConfigPath False
         >>= readMergePersConfig defUserConfigPath  True
     -- TODO: ensure that paths exist ?
-    paths -> foldl (\prev p -> prev >>= readMergePersConfig p False)
-                   (return cmdlineConfig)
-                   paths
+    paths -> foldl (\prev p -> prev >>= readMergePersConfig p False) (return cmdlineConfig) paths
   return $ cZipWith fromOptionIdentity staticDefaultConfig merged