Fix hlint suggestions, update hlint.yaml (#6680)

* Fix hlint suggestions, update hlint.yaml

Most suggestions were redundant brackets. Some required
LambdaCase.

The .hlint.yaml file had a small typo, and didn't ignore camelCase
suggestions in certain modules.

.hlint.yaml

@@ -74,8 +74,10 @@
 - ignore:
     name: "Use camelCase"
     within:
+      - Tests.Writers.Docbook
+      - Tests.Writers.Native
       - Text.Pandoc.Extensions
-      - Text.Pandoc.Lua.Marshalling.Version
+      - Text.Pandoc.Lua.Marshaling.Version
       - Text.Pandoc.Readers.Odt.ContentReader
       - Text.Pandoc.Readers.Odt.Namespaces
 

benchmark/weigh-pandoc.hs

@@ -42,7 +42,7 @@ weighWriter :: Pandoc -> String -> (Pandoc -> Text) -> Weigh ()
 weighWriter doc name writer = func (name ++ " writer") writer doc
 
 weighReader :: Pandoc -> Text -> (Text -> Pandoc) -> Weigh ()
-weighReader doc name reader = do
+weighReader doc name reader =
   case lookup name writers of
        Just (TextWriter writer) ->
          let inp = either (error . show) id $ runPure $ writer def{ writerWrapText = WrapAuto} doc

src/Text/Pandoc/App/CommandLineOptions.hs

@@ -1,4 +1,5 @@
 {-# LANGUAGE CPP                 #-}
+{-# LANGUAGE LambdaCase          #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TupleSections       #-}
 {-# LANGUAGE OverloadedStrings   #-}
@@ -868,9 +869,7 @@ options =
     , Option "" ["print-highlight-style"]
                  (ReqArg
                   (\arg opt -> do
-                     let write = case optOutputFile opt of
-                                        Just f  -> B.writeFile f
-                                        Nothing -> B.putStr
+                     let write = maybe B.putStr B.writeFile $ optOutputFile opt
                      sty <- runIOorExplode $ lookupHighlightStyle arg
                      write $ encodePretty'
                        defConfig{confIndent = Spaces 4
@@ -1017,7 +1016,7 @@ lookupHighlightStyle s
 deprecatedOption :: String -> String -> IO ()
 deprecatedOption o msg =
   runIO (report $ Deprecated (T.pack o) (T.pack msg)) >>=
-    \r -> case r of
+    \case
        Right () -> return ()
        Left e   -> E.throwIO e
 

src/Text/Pandoc/Class/PandocMonad.hs

@@ -433,7 +433,7 @@ getDefaultReferenceDocx = do
                "word/theme/theme1.xml"]
   let toLazy = BL.fromChunks . (:[])
   let pathToEntry path = do
-        epochtime <- (floor . utcTimeToPOSIXSeconds) <$> getCurrentTime
+        epochtime <- floor . utcTimeToPOSIXSeconds <$> getCurrentTime
         contents <- toLazy <$> readDataFile ("docx/" ++ path)
         return $ toEntry path epochtime contents
   datadir <- getUserDataDir
@@ -536,7 +536,7 @@ getDefaultReferencePptx = do
               ]
   let toLazy = BL.fromChunks . (:[])
   let pathToEntry path = do
-        epochtime <- (floor . utcTimeToPOSIXSeconds) <$> getCurrentTime
+        epochtime <- floor . utcTimeToPOSIXSeconds <$> getCurrentTime
         contents <- toLazy <$> readDataFile ("pptx/" ++ path)
         return $ toEntry path epochtime contents
   datadir <- getUserDataDir
@@ -568,11 +568,11 @@ readDataFile fname = do
 -- | Read file from from Cabal data directory.
 readDefaultDataFile :: PandocMonad m => FilePath -> m B.ByteString
 readDefaultDataFile "reference.docx" =
-  (B.concat . BL.toChunks . fromArchive) <$> getDefaultReferenceDocx
+  B.concat . BL.toChunks . fromArchive <$> getDefaultReferenceDocx
 readDefaultDataFile "reference.pptx" =
-  (B.concat . BL.toChunks . fromArchive) <$> getDefaultReferencePptx
+  B.concat . BL.toChunks . fromArchive <$> getDefaultReferencePptx
 readDefaultDataFile "reference.odt" =
-  (B.concat . BL.toChunks . fromArchive) <$> getDefaultReferenceODT
+  B.concat . BL.toChunks . fromArchive <$> getDefaultReferenceODT
 readDefaultDataFile fname =
 #ifdef EMBED_DATA_FILES
   case lookup (makeCanonical fname) dataFiles of

src/Text/Pandoc/Image.hs

@@ -1,5 +1,4 @@
 {-# LANGUAGE OverloadedStrings, ScopedTypeVariables, CPP #-}
-{-# LANGUAGE ViewPatterns      #-}
 {- |
 Module      : Text.Pandoc.Image
 Copyright   : Copyright (C) 2020 John MacFarlane

src/Text/Pandoc/Logging.hs

@@ -1,5 +1,6 @@
 {-# LANGUAGE DeriveDataTypeable #-}
 {-# LANGUAGE DeriveGeneric      #-}
+{-# LANGUAGE LambdaCase         #-}
 {-# LANGUAGE OverloadedStrings  #-}
 {- |
    Module      : Text.Pandoc.Logging
@@ -51,8 +52,7 @@ instance FromJSON Verbosity where
   parseJSON _      =  mzero
 
 instance FromYAML Verbosity where
-  parseYAML = withStr "Verbosity" $ \t ->
-    case t of
+  parseYAML = withStr "Verbosity" $ \case
          "ERROR"   -> return ERROR
          "WARNING" -> return WARNING
          "INFO"    -> return INFO

src/Text/Pandoc/Lua/Marshaling/AST.hs

@@ -230,9 +230,7 @@ peekCaption idx = do
 instance Peekable ColWidth where
   peek idx = do
     width <- Lua.fromOptional <$> Lua.peek idx
-    return $ case width of
-      Nothing -> ColWidthDefault
-      Just w  -> ColWidth w
+    return $ maybe ColWidthDefault ColWidth width
 
 instance Pushable ColWidth where
   push = \case

src/Text/Pandoc/Lua/Module/Utils.hs

@@ -50,9 +50,8 @@ pushModule = do
 -- | Squashes a list of blocks into inlines.
 blocksToInlines :: [Block] -> Lua.Optional [Inline] -> PandocLua [Inline]
 blocksToInlines blks optSep = liftPandocLua $ do
-  let sep = case Lua.fromOptional optSep of
-              Just x -> B.fromList x
-              Nothing -> Shared.defaultBlocksSeparator
+  let sep = maybe Shared.defaultBlocksSeparator B.fromList
+            $ Lua.fromOptional optSep
   return $ B.toList (Shared.blocksToInlinesWithSep sep blks)
 
 -- | Convert list of Pandoc blocks into sections using Divs.

src/Text/Pandoc/Options.hs

@@ -1,8 +1,9 @@
 {-# LANGUAGE CPP                #-}
 {-# LANGUAGE DeriveDataTypeable #-}
 {-# LANGUAGE DeriveGeneric      #-}
-{-# LANGUAGE TemplateHaskell    #-}
+{-# LANGUAGE LambdaCase         #-}
 {-# LANGUAGE OverloadedStrings  #-}
+{-# LANGUAGE TemplateHaskell    #-}
 {- |
    Module      : Text.Pandoc.Options
    Copyright   : Copyright (C) 2012-2020 John MacFarlane
@@ -327,7 +328,7 @@ $(deriveJSON defaultOptions{ constructorTagModifier =
                            } ''CiteMethod)
 
 $(deriveJSON defaultOptions{ constructorTagModifier =
-                            \t -> case t of
+                            \case
                                     "NoObfuscation"         -> "none"
                                     "ReferenceObfuscation"  -> "references"
                                     "JavascriptObfuscation" -> "javascript"

src/Text/Pandoc/PDF.hs

@@ -1,4 +1,5 @@
 {-# LANGUAGE CPP                 #-}
+{-# LANGUAGE LambdaCase          #-}
 {-# LANGUAGE OverloadedStrings   #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {- |
@@ -201,8 +202,7 @@ convertImage opts tmpdir fname = do
       (\(e :: E.SomeException) -> return $ Left $
           "check that rsvg-convert is in path.\n" <>
           tshow e)
-    _ -> JP.readImage fname >>= \res ->
-          case res of
+    _ -> JP.readImage fname >>= \case
                Left e    -> return $ Left $ T.pack e
                Right img ->
                  E.catch (Right pngOut <$ JP.savePngImage pngOut img) $

src/Text/Pandoc/Parsing.hs

@@ -574,15 +574,15 @@ romanNumeral upperCase = do
     let fivehundred = rchar 'D'
     let thousand    = rchar 'M'
     lookAhead $ choice [one, five, ten, fifty, hundred, fivehundred, thousand]
-    thousands <- ((1000 *) . length) <$> many thousand
+    thousands <- (1000 *) . length <$> many thousand
     ninehundreds <- option 0 $ try $ hundred >> thousand >> return 900
     fivehundreds <- option 0 $ 500 <$ fivehundred
     fourhundreds <- option 0 $ try $ hundred >> fivehundred >> return 400
-    hundreds <- ((100 *) . length) <$> many hundred
+    hundreds <- (100 *) . length <$> many hundred
     nineties <- option 0 $ try $ ten >> hundred >> return 90
     fifties <- option 0 (50 <$ fifty)
     forties <- option 0 $ try $ ten >> fifty >> return 40
-    tens <- ((10 *) . length) <$> many ten
+    tens <- (10 *) . length <$> many ten
     nines <- option 0 $ try $ one >> ten >> return 9
     fives <- option 0 (5 <$ five)
     fours <- option 0 $ try $ one >> five >> return 4
@@ -951,7 +951,7 @@ tableWith' headerParser rowParser lineParser footerParser = try $ do
                     then replicate (length aligns) 0.0
                     else widthsFromIndices numColumns indices
     let toRow =  Row nullAttr . map B.simpleCell
-        toHeaderRow l = if null l then [] else [toRow l]
+        toHeaderRow l = [toRow l | not (null l)]
     return (aligns, widths, toHeaderRow <$> heads, map toRow <$> lines')
 
 -- Calculate relative widths of table columns, based on indices
@@ -1170,7 +1170,7 @@ class HasReaderOptions st where
   extractReaderOptions :: st -> ReaderOptions
   getOption            :: (Stream s m t) => (ReaderOptions -> b) -> ParserT s st m b
   -- default
-  getOption  f         = (f . extractReaderOptions) <$> getState
+  getOption  f         = f . extractReaderOptions <$> getState
 
 instance HasReaderOptions ParserState where
   extractReaderOptions = stateOptions
@@ -1492,10 +1492,8 @@ extractIdClass :: Attr -> Attr
 extractIdClass (ident, cls, kvs) = (ident', cls', kvs')
   where
     ident' = fromMaybe ident (lookup "id" kvs)
-    cls'   = case lookup "class" kvs of
-               Just cl -> T.words cl
-               Nothing -> cls
-    kvs'  = filter (\(k,_) -> k /= "id" || k /= "class") kvs
+    cls'   = maybe cls T.words $ lookup "class" kvs
+    kvs'   = filter (\(k,_) -> k /= "id" || k /= "class") kvs
 
 insertIncludedFile' :: (PandocMonad m, HasIncludeFiles st)
                     => ParserT a st m (mf Blocks)

src/Text/Pandoc/Readers/CSV.hs

@@ -39,7 +39,7 @@ readCSV _opts s =
              numcols = length r
              toplain = B.simpleCell . B.plain . B.text . T.strip
              toRow = Row nullAttr . map toplain
-             toHeaderRow l = if null l then [] else [toRow l]
+             toHeaderRow l = [toRow l | not (null l)]
              hdrs = toHeaderRow r
              rows = map toRow rs
              aligns = replicate numcols AlignDefault

src/Text/Pandoc/Readers/CommonMark.hs

@@ -1,6 +1,5 @@
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE ViewPatterns      #-}
 {- |
    Module      : Text.Pandoc.Readers.CommonMark
    Copyright   : Copyright (C) 2015-2020 John MacFarlane

src/Text/Pandoc/Readers/DocBook.hs

@@ -18,7 +18,7 @@ import Data.Either (rights)
 import Data.Foldable (asum)
 import Data.Generics
 import Data.List (intersperse,elemIndex)
-import Data.Maybe (fromMaybe,catMaybes)
+import Data.Maybe (fromMaybe,mapMaybe)
 import Data.Text (Text)
 import qualified Data.Text as T
 import Text.HTML.TagSoup.Entity (lookupEntity)
@@ -781,7 +781,7 @@ parseBlock (Elem e) =
         "para"  -> parseMixed para (elContent e)
         "formalpara" -> do
            tit <- case filterChild (named "title") e of
-                        Just t  -> (para . strong . (<> str ".")) <$>
+                        Just t  -> para . strong . (<> str ".") <$>
                                      getInlines t
                         Nothing -> return mempty
            (tit <>) <$> parseMixed para (elContent e)
@@ -897,7 +897,7 @@ parseBlock (Elem e) =
          parseBlockquote = do
             attrib <- case filterChild (named "attribution") e of
                              Nothing  -> return mempty
-                             Just z   -> (para . (str "— " <>) . mconcat)
+                             Just z   -> para . (str "— " <>) . mconcat
                                          <$>
                                               mapM parseInline (elContent z)
             contents <- getBlocks e
@@ -931,7 +931,7 @@ parseBlock (Elem e) =
                                            _      -> filterChildren isColspec e'
                       let colnames = case colspecs of
                                        [] -> []
-                                       cs -> catMaybes $ map (findAttr (unqual "colname" )) cs
+                                       cs -> mapMaybe (findAttr (unqual "colname" )) cs
                       let isRow x = named "row" x || named "tr" x
                       headrows <- case filterChild (named "thead") e' of
                                        Just h  -> case filterChild isRow h of
@@ -968,7 +968,7 @@ parseBlock (Elem e) =
                                                             in  ColWidth . (/ tot) <$> ws'
                                                 Nothing  -> replicate numrows ColWidthDefault
                       let toRow = Row nullAttr
-                          toHeaderRow l = if null l then [] else [toRow l]
+                          toHeaderRow l = [toRow l | not (null l)]
                       return $ table (simpleCaption $ plain capt)
                                      (zip aligns widths)
                                      (TableHead nullAttr $ toHeaderRow headrows)
@@ -1008,7 +1008,7 @@ parseBlock (Elem e) =
 parseMixed :: PandocMonad m => (Inlines -> Blocks) -> [Content] -> DB m Blocks
 parseMixed container conts = do
   let (ils,rest) = break isBlockElement conts
-  ils' <- (trimInlines . mconcat) <$> mapM parseInline ils
+  ils' <- trimInlines . mconcat <$> mapM parseInline ils
   let p = if ils' == mempty then mempty else container ils'
   case rest of
     [] -> return p
@@ -1036,10 +1036,10 @@ parseEntry cn el = do
         case (mStrt, mEnd) of
           (Just start, Just end) -> colDistance start end
           _ -> 1
-  (fmap (cell AlignDefault 1 (toColSpan el)) . (parseMixed plain) . elContent) el
+  (fmap (cell AlignDefault 1 (toColSpan el)) . parseMixed plain . elContent) el
 
 getInlines :: PandocMonad m => Element -> DB m Inlines
-getInlines e' = (trimInlines . mconcat) <$>
+getInlines e' = trimInlines . mconcat <$>
                  mapM parseInline (elContent e')
 
 strContentRecursive :: Element -> String
@@ -1136,7 +1136,7 @@ parseInline (Elem e) =
                              "strong"        -> strong <$> innerInlines
                              "strikethrough" -> strikeout <$> innerInlines
                              _               -> emph <$> innerInlines
-        "footnote" -> (note . mconcat) <$>
+        "footnote" -> note . mconcat <$>
                          mapM parseBlock (elContent e)
         "title" -> return mempty
         "affiliation" -> skip
@@ -1149,14 +1149,14 @@ parseInline (Elem e) =
            lift $ report $ IgnoredElement $ T.pack $ qName (elName e)
            return mempty
 
-         innerInlines = (trimInlines . mconcat) <$>
+         innerInlines = trimInlines . mconcat <$>
                           mapM parseInline (elContent e)
          codeWithLang = do
            let classes' = case attrValue "language" e of
                                "" -> []
                                l  -> [l]
            return $ codeWith (attrValue "id" e,classes',[]) $ T.pack $ strContentRecursive e
-         simpleList = (mconcat . intersperse (str "," <> space)) <$> mapM getInlines
+         simpleList = mconcat . intersperse (str "," <> space) <$> mapM getInlines
                          (filterChildren (named "member") e)
          segmentedList = do
            tit <- maybe (return mempty) getInlines $ filterChild (named "title") e

src/Text/Pandoc/Readers/Docx.hs

@@ -91,9 +91,9 @@ readDocx :: PandocMonad m
          => ReaderOptions
          -> B.ByteString
          -> m Pandoc
-readDocx opts bytes = do
+readDocx opts bytes =
   case toArchiveOrFail bytes of
-    Right archive -> do
+    Right archive ->
       case archiveToDocxWithWarnings archive of
         Right (docx, parserWarnings) -> do
           mapM_ (P.report . DocxParserWarning) parserWarnings
@@ -291,9 +291,9 @@ runStyleToTransform rPr' = do
             spanWith ("",[],[("dir","ltr")]) . go rPr{isRTL = Nothing}
         | Just SupScrpt <- rVertAlign rPr =
             superscript . go rPr{rVertAlign = Nothing}
-        | Just SubScrpt <- rVertAlign rPr = do
+        | Just SubScrpt <- rVertAlign rPr =
             subscript . go rPr{rVertAlign = Nothing}
-        | Just "single" <- rUnderline rPr = do
+        | Just "single" <- rUnderline rPr =
             Pandoc.underline . go rPr{rUnderline = Nothing}
         | otherwise = id
   return $ go rPr'
@@ -658,7 +658,7 @@ bodyPartToBlocks (Tbl cap _ look parts@(r:rs)) = do
       rowLength (Docx.Row c) = length c
 
   let toRow = Pandoc.Row nullAttr . map simpleCell
-      toHeaderRow l = if null l then [] else [toRow l]
+      toHeaderRow l = [toRow l | not (null l)]
 
   -- pad cells.  New Text.Pandoc.Builder will do that for us,
   -- so this is for compatibility while we switch over.

src/Text/Pandoc/Readers/Docx/Parse.hs

@@ -404,12 +404,8 @@ archiveToNotes zf =
                >>= (parseXMLDoc . UTF8.toStringLazy . fromEntry)
       enElem = findEntryByPath "word/endnotes.xml" zf
                >>= (parseXMLDoc . UTF8.toStringLazy . fromEntry)
-      fn_namespaces = case fnElem of
-        Just e  -> elemToNameSpaces e
-        Nothing -> []
-      en_namespaces = case enElem of
-        Just e  -> elemToNameSpaces e
-        Nothing -> []
+      fn_namespaces = maybe [] elemToNameSpaces fnElem
+      en_namespaces = maybe [] elemToNameSpaces enElem
       ns = unionBy (\x y -> fst x == fst y) fn_namespaces en_namespaces
       fn = fnElem >>= walkDocument ns >>= elemToNotes ns "footnote"
       en = enElem >>= walkDocument ns >>= elemToNotes ns "endnote"
@@ -420,9 +416,7 @@ archiveToComments :: Archive -> Comments
 archiveToComments zf =
   let cmtsElem = findEntryByPath "word/comments.xml" zf
                >>= (parseXMLDoc . UTF8.toStringLazy . fromEntry)
-      cmts_namespaces = case cmtsElem of
-        Just e  -> elemToNameSpaces e
-        Nothing -> []
+      cmts_namespaces = maybe [] elemToNameSpaces cmtsElem
       cmts = elemToComments cmts_namespaces <$> (cmtsElem >>= walkDocument cmts_namespaces)
   in
     case cmts of

src/Text/Pandoc/Readers/DokuWiki.hs

@@ -472,7 +472,7 @@ table = do
                             else ([], rows)
   let attrs = (AlignDefault, ColWidthDefault) <$ transpose rows
   let toRow = Row nullAttr . map B.simpleCell
-      toHeaderRow l = if null l then [] else [toRow l]
+      toHeaderRow l = [toRow l | not (null l)]
   pure $ B.table B.emptyCaption
                  attrs
                  (TableHead nullAttr $ toHeaderRow headerRow)

src/Text/Pandoc/Readers/HTML.hs

@@ -517,7 +517,7 @@ pTable = try $ do
                        else replicate cols (ColWidth (1.0 / fromIntegral cols))
                   else widths'
   let toRow = Row nullAttr . map B.simpleCell
-      toHeaderRow l = if null l then [] else [toRow l]
+      toHeaderRow l = [toRow l | not (null l)]
   return $ B.tableWith attribs
                    (B.simpleCaption $ B.plain caption)
                    (zip aligns widths)

src/Text/Pandoc/Readers/Haddock.hs

@@ -86,7 +86,7 @@ docHToBlocks d' =
                     }
       -> let toCells = map (docHToBlocks . tableCellContents) . tableRowCells
              toRow = Row nullAttr . map B.simpleCell
-             toHeaderRow l = if null l then [] else [toRow l]
+             toHeaderRow l = [toRow l | not (null l)]
              (header, body) =
                if null headerRows
                   then ([], map toCells bodyRows)

src/Text/Pandoc/Readers/JATS.hs

@@ -189,7 +189,7 @@ parseBlock (Elem e) =
         _       -> getBlocks e
    where parseMixed container conts = do
            let (ils,rest) = break isBlockElement conts
-           ils' <- (trimInlines . mconcat) <$> mapM parseInline ils
+           ils' <- trimInlines . mconcat <$> mapM parseInline ils
            let p = if ils' == mempty then mempty else container ils'
            case rest of
                  []     -> return p
@@ -206,7 +206,7 @@ parseBlock (Elem e) =
          parseBlockquote = do
             attrib <- case filterChild (named "attribution") e of
                              Nothing  -> return mempty
-                             Just z   -> (para . (str "— " <>) . mconcat)
+                             Just z   -> para . (str "— " <>) . mconcat
                                          <$>
                                               mapM parseInline (elContent z)
             contents <- getBlocks e
@@ -281,7 +281,7 @@ parseBlock (Elem e) =
                                                             in  ColWidth . (/ tot) <$> ws'
                                                 Nothing  -> replicate numrows ColWidthDefault
                       let toRow = Row nullAttr . map simpleCell
-                          toHeaderRow l = if null l then [] else [toRow l]
+                          toHeaderRow l = [toRow l | not (null l)]
                       return $ table (simpleCaption $ plain capt)
                                      (zip aligns widths)
                                      (TableHead nullAttr $ toHeaderRow headrows)
@@ -309,7 +309,7 @@ parseBlock (Elem e) =
                      return $ headerWith (ident,[],[]) n' headerText <> b
 
 getInlines :: PandocMonad m => Element -> JATS m Inlines
-getInlines e' = (trimInlines . mconcat) <$>
+getInlines e' = trimInlines . mconcat <$>
                  mapM parseInline (elContent e')
 
 parseMetadata :: PandocMonad m => Element -> JATS m Blocks
@@ -518,10 +518,10 @@ parseInline (Elem e) =
         "email" -> return $ link ("mailto:" <> textContent e) ""
                           $ str $ textContent e
         "uri" -> return $ link (textContent e) "" $ str $ textContent e
-        "fn" -> (note . mconcat) <$>
+        "fn" -> note . mconcat <$>
                          mapM parseBlock (elContent e)
         _          -> innerInlines
-   where innerInlines = (trimInlines . mconcat) <$>
+   where innerInlines = trimInlines . mconcat <$>
                           mapM parseInline (elContent e)
          mathML x =
             case readMathML . T.pack . showElement $ everywhere (mkT removePrefix) x of

src/Text/Pandoc/Readers/LaTeX.hs

@@ -31,6 +31,7 @@ import Control.Monad
 import Control.Monad.Except (throwError)
 import Data.Char (isDigit, isLetter, toUpper, chr)
 import Data.Default
+import Data.Functor (($>))
 import Data.List (intercalate)
 import qualified Data.Map as M
 import Data.Maybe (fromMaybe, maybeToList)
@@ -136,15 +137,15 @@ rawLaTeXBlock = do
   inp <- getInput
   let toks = tokenize "source" inp
   snd <$> (rawLaTeXParser toks False (macroDef (const mempty)) blocks
-      <|> (rawLaTeXParser toks True
+      <|> rawLaTeXParser toks True
              (do choice (map controlSeq
                    ["include", "input", "subfile", "usepackage"])
                  skipMany opt
                  braced
-                 return mempty) blocks)
+                 return mempty) blocks
       <|> rawLaTeXParser toks True
            (environment <|> blockCommand)
-           (mconcat <$> (many (block <|> beginOrEndCommand))))
+           (mconcat <$> many (block <|> beginOrEndCommand)))
 
 -- See #4667 for motivation; sometimes people write macros
 -- that just evaluate to a begin or end command, which blockCommand
@@ -187,10 +188,10 @@ inlineCommand = do
 -- inline elements:
 
 word :: PandocMonad m => LP m Inlines
-word = (str . untoken) <$> satisfyTok isWordTok
+word = str . untoken <$> satisfyTok isWordTok
 
 regularSymbol :: PandocMonad m => LP m Inlines
-regularSymbol = (str . untoken) <$> satisfyTok isRegularSymbol
+regularSymbol = str . untoken <$> satisfyTok isRegularSymbol
   where isRegularSymbol (Tok _ Symbol t) = not $ T.any isSpecial t
         isRegularSymbol _                = False
         isSpecial c = c `Set.member` specialChars
@@ -206,7 +207,7 @@ inlineGroup = do
 
 doLHSverb :: PandocMonad m => LP m Inlines
 doLHSverb =
-  (codeWith ("",["haskell"],[]) . untokenize)
+  codeWith ("",["haskell"],[]) . untokenize
     <$> manyTill (satisfyTok (not . isNewlineTok)) (symbol '|')
 
 mkImage :: PandocMonad m => [(Text, Text)] -> Text -> LP m Inlines
@@ -342,7 +343,7 @@ doverb = do
               Just (c, ts) | T.null ts -> return c
               _            -> mzero
   withVerbatimMode $
-    (code . untokenize) <$>
+    code . untokenize <$>
       manyTill (notFollowedBy newlineTok >> verbTok marker) (symbol marker)
 
 verbTok :: PandocMonad m => Char -> LP m Tok
@@ -383,7 +384,7 @@ doinlinecode classes = do
               _            -> mzero
   let stopchar = if marker == '{' then '}' else marker
   withVerbatimMode $
-    (codeWith ("",classes,[]) . T.map nlToSpace . untokenize) <$>
+    codeWith ("",classes,[]) . T.map nlToSpace . untokenize <$>
       manyTill (verbTok stopchar) (symbol stopchar)
 
 nlToSpace :: Char -> Char
@@ -402,7 +403,7 @@ dollarsMath = do
   display <- option False (True <$ symbol '$')
   (do contents <- try $ untokenize <$> pDollarsMath 0
       if display
-         then (mathDisplay contents <$ symbol '$')
+         then mathDisplay contents <$ symbol '$'
          else return $ mathInline contents)
    <|> (guard display >> return (mathInline ""))
 
@@ -415,7 +416,7 @@ pDollarsMath n = do
               , n == 0 -> return []
               | t == "\\" -> do
                   tk' <- anyTok
-                  ((tk :) . (tk' :)) <$> pDollarsMath n
+                  (tk :) . (tk' :) <$> pDollarsMath n
               | t == "{" -> (tk :) <$> pDollarsMath (n+1)
               | t == "}" ->
                 if n > 0
@@ -477,7 +478,7 @@ cites mode multi = try $ do
                tempCits <- many1 simpleCiteArgs
                case tempCits of
                  (k:ks) -> case ks of
-                             (_:_) -> return $ ((addMprenote pre k):init ks) ++
+                             (_:_) -> return $ (addMprenote pre k : init ks) ++
                                                  [addMpostnote suf (last ks)]
                              _ -> return [addMprenote pre (addMpostnote suf k)]
                  _ -> return [[]]
@@ -521,7 +522,7 @@ complexNatbibCitation mode = try $ do
       bgroup
       items <- mconcat <$>
                 many1 (notFollowedBy (symbol ';') >> inline)
-                  `sepBy1` (symbol ';')
+                  `sepBy1` symbol ';'
       egroup
       return $ map handleCitationPart items
   case cs of
@@ -660,7 +661,7 @@ inlineCommands = M.union inlineLanguageCommands $ M.fromList
   , ("eqref", rawInlineOr "eqref" $ doref "eqref")   -- from amsmath.sty
   , ("mbox", rawInlineOr "mbox" $ processHBox <$> tok)
   , ("hbox", rawInlineOr "hbox" $ processHBox <$> tok)
-  , ("lettrine", rawInlineOr "lettrine" $ lettrine)
+  , ("lettrine", rawInlineOr "lettrine" lettrine)
   , ("(", mathInline . untokenize <$> manyTill anyTok (controlSeq ")"))
   , ("[", mathDisplay . untokenize <$> manyTill anyTok (controlSeq "]"))
   , ("ensuremath", mathInline . untokenize <$> braced)
@@ -1073,7 +1074,7 @@ coloredInline stylename = do
   spanWith ("",[],[("style",stylename <> ": " <> untokenize color)]) <$> tok
 
 ttfamily :: PandocMonad m => LP m Inlines
-ttfamily = (code . stringify . toList) <$> tok
+ttfamily = code . stringify . toList <$> tok
 
 rawInlineOr :: PandocMonad m => Text -> LP m Inlines -> LP m Inlines
 rawInlineOr name' fallback = do
@@ -1235,8 +1236,8 @@ doSubfile = do
 include :: (PandocMonad m, Monoid a) => Text -> LP m a
 include name = do
   skipMany opt
-  fs <- (map (T.unpack . removeDoubleQuotes . T.strip) . T.splitOn "," .
-         untokenize) <$> braced
+  fs <- map (T.unpack . removeDoubleQuotes . T.strip) . T.splitOn "," .
+         untokenize <$> braced
   let defaultExt | name == "usepackage" = ".sty"
                  | otherwise            = ".tex"
   mapM_ (insertIncluded defaultExt) fs
@@ -1251,7 +1252,7 @@ insertIncluded defaultExtension f' = do
                 ".tex" -> f'
                 ".sty" -> f'
                 _      -> addExtension f' defaultExtension
-  dirs <- (map T.unpack . splitTextBy (==':') . fromMaybe ".") <$> lookupEnv "TEXINPUTS"
+  dirs <- map T.unpack . splitTextBy (==':') . fromMaybe "." <$> lookupEnv "TEXINPUTS"
   pos <- getPosition
   containers <- getIncludeFiles <$> getState
   when (T.pack f `elem` containers) $
@@ -1564,7 +1565,7 @@ blockCommands = M.fromList
    , ("frametitle", section nullAttr 3)
    , ("framesubtitle", section nullAttr 4)
    -- letters
-   , ("opening", (para . trimInlines) <$> (skipopts *> tok))
+   , ("opening", para . trimInlines <$> (skipopts *> tok))
    , ("closing", skipopts *> closing)
    -- memoir
    , ("plainbreak", braced >> pure horizontalRule)
@@ -1578,10 +1579,10 @@ blockCommands = M.fromList
    --
    , ("hrule", pure horizontalRule)
    , ("strut", pure mempty)
-   , ("rule", skipopts *> tok *> tok *> pure horizontalRule)
+   , ("rule", skipopts *> tok *> tok $> horizontalRule)
    , ("item", looseItem)
    , ("documentclass", skipopts *> braced *> preamble)
-   , ("centerline", (para . trimInlines) <$> (skipopts *> tok))
+   , ("centerline", para . trimInlines <$> (skipopts *> tok))
    , ("caption", mempty <$ setCaption)
    , ("bibliography", mempty <$ (skipopts *> braced >>=
          addMeta "bibliography" . splitBibs . untokenize))
@@ -1623,7 +1624,7 @@ environments :: PandocMonad m => M.Map Text (LP m Blocks)
 environments = M.fromList
    [ ("document", env "document" blocks <* skipMany anyTok)
    , ("abstract", mempty <$ (env "abstract" blocks >>= addMeta "abstract"))
-   , ("sloppypar", env "sloppypar" $ blocks)
+   , ("sloppypar", env "sloppypar" blocks)
    , ("letter", env "letter" letterContents)
    , ("minipage", env "minipage" $
           skipopts *> spaces *> optional braced *> spaces *> blocks)
@@ -1709,7 +1710,7 @@ proof = do
   bs <- env "proof" blocks
   return $
     B.divWith ("", ["proof"], []) $
-      addQed $ addTitle (B.emph (title <> ".")) $ bs
+      addQed $ addTitle (B.emph (title <> ".")) bs
 
 addTitle :: Inlines -> Blocks -> Blocks
 addTitle ils bs =
@@ -1753,8 +1754,7 @@ theoremEnvironment name = do
             then do
                let name' = fromMaybe name $ theoremSeries tspec
                num <- getNextNumber
-                   (fromMaybe (DottedNum [0]) .
-                    fmap theoremLastNum .
+                   (maybe (DottedNum [0]) theoremLastNum .
                     M.lookup name' . sTheoremMap)
                updateState $ \s ->
                  s{ sTheoremMap =
@@ -1866,7 +1866,7 @@ inputMinted = do
   pos <- getPosition
   attr <- mintedAttr
   f <- T.filter (/='"') . untokenize <$> braced
-  dirs <- (map T.unpack . splitTextBy (==':') . fromMaybe ".") <$> lookupEnv "TEXINPUTS"
+  dirs <- map T.unpack . splitTextBy (==':') . fromMaybe "." <$> lookupEnv "TEXINPUTS"
   mbCode <- readFileFromDirs dirs (T.unpack f)
   rawcode <- case mbCode of
                   Just s -> return s
@@ -1979,7 +1979,7 @@ inputListing = do
   pos <- getPosition
   options <- option [] keyvals
   f <- T.filter (/='"') . untokenize <$> braced
-  dirs <- (map T.unpack . splitTextBy (==':') . fromMaybe ".") <$> lookupEnv "TEXINPUTS"
+  dirs <- map T.unpack . splitTextBy (==':') . fromMaybe "." <$> lookupEnv "TEXINPUTS"
   mbCode <- readFileFromDirs dirs (T.unpack f)
   codeLines <- case mbCode of
                       Just s -> return $ T.lines s
@@ -2176,18 +2176,17 @@ parseTableCell :: PandocMonad m => LP m Cell
 parseTableCell = do
   spaces
   updateState $ \st -> st{ sInTableCell = True }
-  cell' <- ( multicolumnCell
+  cell' <-   multicolumnCell
          <|> multirowCell
          <|> parseSimpleCell
          <|> parseEmptyCell
-           )
   updateState $ \st -> st{ sInTableCell = False }
   spaces
   return cell'
   where
     -- The parsing of empty cells is important in LaTeX, especially when dealing
     -- with multirow/multicolumn. See #6603.
-    parseEmptyCell = optional spaces >> return emptyCell <* optional spaces
+    parseEmptyCell = spaces $> emptyCell
 
 cellAlignment :: PandocMonad m => LP m Alignment
 cellAlignment = skipMany (symbol '|') *> alignment <* skipMany (symbol '|')
@@ -2237,8 +2236,8 @@ multicolumnCell = controlSeq "multicolumn" >> do
         (Cell _ _ (RowSpan rs) _ bs) <- multirowCell
         return $ cell
                   alignment
-                  (RowSpan $ rs)
-                  (ColSpan $ span')
+                  (RowSpan rs)
+                  (ColSpan span')
                   (fromList bs)
 
   symbol '{' *> (nestedCell <|> singleCell) <* symbol '}'
@@ -2276,7 +2275,7 @@ simpTable envname hasWidthParameter = try $ do
   lookAhead $ controlSeq "end" -- make sure we're at end
   return $ table emptyCaption
                  (zip aligns widths)
-                 (TableHead nullAttr $ header')
+                 (TableHead nullAttr header')
                  [TableBody nullAttr 0 [] rows]
                  (TableFoot nullAttr [])
 

src/Text/Pandoc/Readers/LaTeX/Lang.hs

@@ -152,4 +152,4 @@ babelLangToBCP47 s =
        "newzealand" -> Just $ Lang "en" "" "NZ" []
        "american" -> Just $ Lang "en" "" "US" []
        "classiclatin" -> Just $ Lang "la" "" "" ["x-classic"]
-       _ -> fmap ($ "") $ M.lookup s polyglossiaLangToBCP47
+       _ -> ($ "") <$> M.lookup s polyglossiaLangToBCP47

src/Text/Pandoc/Readers/LaTeX/Parsing.hs

@@ -1,8 +1,8 @@
 {-# LANGUAGE FlexibleInstances     #-}
+{-# LANGUAGE LambdaCase            #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE OverloadedStrings     #-}
 {-# LANGUAGE ScopedTypeVariables   #-}
-{-# LANGUAGE ViewPatterns          #-}
 {- |
    Module      : Text.Pandoc.Readers.LaTeX.Parsing
    Copyright   : Copyright (C) 2006-2020 John MacFarlane
@@ -736,14 +736,14 @@ keyval = try $ do
              (mconcat <$> many1 (
                  (untokenize . snd <$> withRaw braced)
                  <|>
-                 (untokenize <$> (many1
+                 (untokenize <$> many1
                       (satisfyTok
-                         (\t -> case t of
+                         (\case
                                 Tok _ Symbol "]" -> False
                                 Tok _ Symbol "," -> False
                                 Tok _ Symbol "{" -> False
                                 Tok _ Symbol "}" -> False
-                                _                -> True))))))
+                                _                -> True)))))
   optional (symbol ',')
   sp
   return (key, T.strip val)
@@ -756,8 +756,7 @@ verbEnv name = withVerbatimMode $ do
   optional blankline
   res <- manyTill anyTok (end_ name)
   return $ stripTrailingNewline
-         $ untokenize
-         $ res
+         $ untokenize res
 
 -- Strip single final newline and any spaces following it.
 -- Input is unchanged if it doesn't end with newline +
@@ -819,8 +818,7 @@ overlaySpecification = try $ do
 
 overlayTok :: PandocMonad m => LP m Tok
 overlayTok =
-  satisfyTok (\t ->
-                  case t of
+  satisfyTok (\case
                     Tok _ Word _       -> True
                     Tok _ Spaces _     -> True
                     Tok _ Symbol c     -> c `elem` ["-","+","@","|",":",","]

src/Text/Pandoc/Readers/LaTeX/SIunitx.hs

@@ -103,9 +103,9 @@ doSIang = do
   ps <- T.splitOn ";" . untokenize <$> braced
   case ps ++ repeat "" of
     (d:m:s:_) -> return $
-      (if T.null d then mempty else (str d <> str "\xb0")) <>
-      (if T.null m then mempty else (str m <> str "\x2032")) <>
-      (if T.null s then mempty else (str s <> str "\x2033"))
+      (if T.null d then mempty else str d <> str "\xb0") <>
+      (if T.null m then mempty else str m <> str "\x2032") <>
+      (if T.null s then mempty else str s <> str "\x2033")
     _ -> return mempty
 
 -- converts e.g. \SIrange{100}{200}{\ms} to "100 ms--200 ms"

src/Text/Pandoc/Readers/Man.hs

@@ -162,7 +162,7 @@ parseTable = do
       _   -> Nothing
 
   toRow = Row nullAttr . map simpleCell
-  toHeaderRow l = if null l then [] else [toRow l]
+  toHeaderRow l = [toRow l | not (null l)]
 
 parseNewParagraph :: PandocMonad m => ManParser m Blocks
 parseNewParagraph = do

src/Text/Pandoc/Readers/Markdown.hs

@@ -1025,7 +1025,7 @@ htmlBlock = do
   guardEnabled Ext_raw_html
   try (do
       (TagOpen _ attrs) <- lookAhead $ fst <$> htmlTag isBlockTag
-      (return . B.rawBlock "html") <$> rawVerbatimBlock
+      return . B.rawBlock "html" <$> rawVerbatimBlock
         <|> (do guardEnabled Ext_markdown_attribute
                 oldMarkdownAttribute <- stateMarkdownAttribute <$> getState
                 markdownAttribute <-
@@ -1582,7 +1582,7 @@ ender c n = try $ do
 three :: PandocMonad m => Char -> MarkdownParser m (F Inlines)
 three c = do
   contents <- mconcat <$> many (notFollowedBy (ender c 1) >> inline)
-  (ender c 3 >> updateLastStrPos >> return ((B.strong . B.emph) <$> contents))
+  (ender c 3 >> updateLastStrPos >> return (B.strong . B.emph <$> contents))
     <|> (ender c 2 >> updateLastStrPos >> one c (B.strong <$> contents))
     <|> (ender c 1 >> updateLastStrPos >> two c (B.emph <$> contents))
     <|> return (return (B.str $ T.pack [c,c,c]) <> contents)
@@ -1617,7 +1617,7 @@ inlinesBetween :: PandocMonad m
                -> MarkdownParser m b
                -> MarkdownParser m (F Inlines)
 inlinesBetween start end =
-  (trimInlinesF . mconcat) <$> try (start >> many1Till inner end)
+  trimInlinesF . mconcat <$> try (start >> many1Till inner end)
     where inner      = innerSpace <|> (notFollowedBy' (() <$ whitespace) >> inline)
           innerSpace = try $ whitespace <* notFollowedBy' end
 
@@ -1720,7 +1720,7 @@ source = do
             try parenthesizedChars
         <|> (notFollowedBy (oneOf " )") >> countChar 1 litChar)
         <|> try (many1Char spaceChar <* notFollowedBy (oneOf "\"')"))
-  let sourceURL = (T.unwords . T.words . T.concat) <$> many urlChunk
+  let sourceURL = T.unwords . T.words . T.concat <$> many urlChunk
   let betweenAngles = try $
          char '<' >> manyTillChar litChar (char '>')
   src <- try betweenAngles <|> sourceURL
@@ -2023,7 +2023,7 @@ textualCite = try $ do
   mbrest <- option Nothing $ try $ spnl >> Just <$> withRaw normalCite
   case mbrest of
        Just (rest, raw) ->
-         return $ (flip B.cite (B.text $ "@" <> key <> " " <> raw) . (first:))
+         return $ flip B.cite (B.text $ "@" <> key <> " " <> raw) . (first:)
                <$> rest
        Nothing   ->
          (do
@@ -2130,4 +2130,4 @@ toRow :: [Blocks] -> Row
 toRow = Row nullAttr . map B.simpleCell
 
 toHeaderRow :: [Blocks] -> [Row]
-toHeaderRow l = if null l then [] else [toRow l]
+toHeaderRow l = [toRow l | not (null l)]

src/Text/Pandoc/Readers/MediaWiki.hs

@@ -231,7 +231,7 @@ table = do
                           then (hdr, rows')
                           else (replicate cols mempty, hdr:rows')
   let toRow = Row nullAttr . map B.simpleCell
-      toHeaderRow l = if null l then [] else [toRow l]
+      toHeaderRow l = [toRow l | not (null l)]
   return $ B.table (B.simpleCaption $ B.plain caption)
                    cellspecs
                    (TableHead nullAttr $ toHeaderRow headers)
@@ -283,7 +283,7 @@ tableCaption = try $ do
   skipSpaces
   sym "|+"
   optional (try $ parseAttrs *> skipSpaces *> char '|' *> blanklines)
-  (trimInlines . mconcat) <$>
+  trimInlines . mconcat <$>
     many (notFollowedBy (cellsep <|> rowsep) *> inline)
 
 tableRow :: PandocMonad m => MWParser m [((Alignment, Double), Blocks)]
@@ -678,7 +678,7 @@ url = do
 -- | Parses a list of inlines between start and end delimiters.
 inlinesBetween :: (PandocMonad m, Show b) => MWParser m a -> MWParser m b -> MWParser m Inlines
 inlinesBetween start end =
-  (trimInlines . mconcat) <$> try (start >> many1Till inner end)
+  trimInlines . mconcat <$> try (start >> many1Till inner end)
     where inner      = innerSpace <|> (notFollowedBy' (() <$ whitespace) >> inline)
           innerSpace = try $ whitespace <* notFollowedBy' end
 

src/Text/Pandoc/Readers/Muse.hs

@@ -653,7 +653,7 @@ museToPandocTable (MuseTable caption headers body footers) =
   where attrs = (AlignDefault, ColWidthDefault) <$ transpose (headers ++ body ++ footers)
         (headRow, rows) = fromMaybe ([], []) $ uncons headers
         toRow = Row nullAttr . map B.simpleCell
-        toHeaderRow l = if null l then [] else [toRow l]
+        toHeaderRow l = [toRow l | not (null l)]
 
 museAppendElement :: MuseTableElement
                   -> MuseTable

src/Text/Pandoc/Readers/Odt/ContentReader.hs

@@ -220,9 +220,9 @@ uniqueIdentFrom :: AnchorPrefix -> [Anchor] -> Anchor
 uniqueIdentFrom baseIdent usedIdents =
   let  numIdent n = baseIdent <> "-" <> T.pack (show n)
   in  if baseIdent `elem` usedIdents
-        then case find (\x -> numIdent x `notElem` usedIdents) ([1..60000] :: [Int]) of
-                  Just x  -> numIdent x
-                  Nothing -> baseIdent   -- if we have more than 60,000, allow repeats
+        then maybe baseIdent numIdent
+             $ find (\x -> numIdent x `notElem` usedIdents) ([1..60000] :: [Int])
+               -- if we have more than 60,000, allow repeats
         else baseIdent
 
 -- | First argument: basis for a new "pretty" anchor if none exists yet

src/Text/Pandoc/Readers/Odt/Generic/XMLConverter.hs

@@ -1,5 +1,6 @@
 {-# LANGUAGE TupleSections   #-}
 {-# LANGUAGE GADTs           #-}
+{-# LANGUAGE LambdaCase      #-}
 {-# LANGUAGE PatternGuards   #-}
 {- |
    Module      : Text.Pandoc.Readers.Odt.Generic.XMLConverter
@@ -691,7 +692,7 @@ makeMatcherC nsID name c = (    second (    contentToElem
                             >>% recover)
                     &&&^ snd
         contentToElem :: FallibleXMLConverter nsID extraState XML.Content XML.Element
-        contentToElem = arr $ \e -> case e of
+        contentToElem = arr $ \case
                                      XML.Elem e' -> succeedWith e'
                                      _           -> failEmpty
 

src/Text/Pandoc/Readers/Org/Blocks.hs

@@ -34,6 +34,7 @@ import Text.Pandoc.Shared (compactify, compactifyDL, safeRead)
 import Control.Monad (foldM, guard, mplus, mzero, void)
 import Data.Char (isSpace)
 import Data.Default (Default)
+import Data.Functor (($>))
 import Data.List (foldl', intersperse)
 import Data.Maybe (fromMaybe, isJust, isNothing)
 import Data.Text (Text)
@@ -103,9 +104,7 @@ attrFromBlockAttributes :: BlockAttributes -> Attr
 attrFromBlockAttributes BlockAttributes{..} =
   let
     ident   = fromMaybe mempty $ lookup "id" blockAttrKeyValues
-    classes = case lookup "class" blockAttrKeyValues of
-                Nothing     -> []
-                Just clsStr -> T.words clsStr
+    classes = maybe [] T.words $ lookup "class" blockAttrKeyValues
     kv      = filter ((`notElem` ["id", "class"]) . fst) blockAttrKeyValues
   in (ident, classes, kv)
 
@@ -576,10 +575,10 @@ rawExportLine = try $ do
 rawOrgLine :: PandocMonad m => OrgParser m (F Blocks)
 rawOrgLine = do
   line <- metaLineStart *> anyLine
-  returnF $ B.rawBlock "org" $ ("#+" <> line)
+  returnF $ B.rawBlock "org" $ "#+" <> line
 
 commentLine :: Monad m => OrgParser m Blocks
-commentLine = commentLineStart *> anyLine *> pure mempty
+commentLine = commentLineStart *> anyLine $> mempty
 
 
 --
@@ -648,12 +647,12 @@ orgToPandocTable (OrgTable colProps heads lns) caption =
              (TableFoot nullAttr [])
  where
    toRow = Row nullAttr . map B.simpleCell
-   toHeaderRow l = if null l then [] else [toRow l]
+   toHeaderRow l = [toRow l | not (null l)]
    convertColProp :: Maybe Int -> ColumnProperty -> (Alignment, ColWidth)
    convertColProp totalWidth colProp =
      let
        align' = fromMaybe AlignDefault $ columnAlignment colProp
-       width' = (\w t -> (fromIntegral w / fromIntegral t))
+       width' = (\w t -> fromIntegral w / fromIntegral t)
                 <$> columnRelWidth colProp
                 <*> totalWidth
      in (align', maybe ColWidthDefault ColWidth width')
@@ -691,9 +690,9 @@ columnPropertyCell = emptyOrgCell <|> propCell <?> "alignment info"
 
 tableAlignFromChar :: Monad m => OrgParser m Alignment
 tableAlignFromChar = try $
-  choice [ char 'l' *> return AlignLeft
-         , char 'c' *> return AlignCenter
-         , char 'r' *> return AlignRight
+  choice [ char 'l' $> AlignLeft
+         , char 'c' $> AlignCenter
+         , char 'r' $> AlignRight
          ]
 
 tableHline :: Monad m => OrgParser m OrgTableRow
@@ -796,13 +795,13 @@ paraOrPlain = try $ do
   -- Make sure we are not looking at a headline
   notFollowedBy' headerStart
   ils <- inlines
-  nl <- option False (newline *> return True)
+  nl <- option False (newline $> True)
   -- Read block as paragraph, except if we are in a list context and the block
   -- is directly followed by a list item, in which case the block is read as
   -- plain text.
   try (guard nl
        *> notFollowedBy (inList *> (orderedListStart <|> bulletListStart))
-       *> return (B.para <$> ils))
+       $> (B.para <$> ils))
     <|>  return (B.plain <$> ils)
 
 

src/Text/Pandoc/Readers/Org/ParserState.hs

@@ -122,7 +122,7 @@ data OrgParserState = OrgParserState
   , orgMacros                    :: M.Map Text Macro
   }
 
-data OrgParserLocal = OrgParserLocal
+newtype OrgParserLocal = OrgParserLocal
   { orgLocalQuoteContext :: QuoteContext
   }
 

src/Text/Pandoc/Readers/Org/Shared.hs

@@ -58,9 +58,7 @@ cleanLinkText s
 originalLang :: Text -> [(Text, Text)]
 originalLang lang =
   let transLang = translateLang lang
-  in if transLang == lang
-     then []
-     else [("org-language", lang)]
+  in [("org-language", lang) | transLang /= lang]
 
 -- | Translate from Org-mode's programming language identifiers to those used
 -- by Pandoc.  This is useful to allow for proper syntax highlighting in

src/Text/Pandoc/Readers/RST.hs

@@ -164,7 +164,7 @@ parseRST = do
                         , stateIdentifiers = mempty }
   -- now parse it for real...
   blocks <- B.toList <$> parseBlocks
-  citations <- (sort . M.toList . stateCitations) <$> getState
+  citations <- sort . M.toList . stateCitations <$> getState
   citationItems <- mapM parseCitation citations
   let refBlock = [Div ("citations",[],[]) $
                  B.toList $ B.definitionList citationItems | not (null citationItems)]
@@ -823,7 +823,7 @@ listTableDirective top fields body = do
                            splitTextBy (`elem` (" ," :: String)) specs
         _ -> replicate numOfCols ColWidthDefault
       toRow = Row nullAttr . map B.simpleCell
-      toHeaderRow l = if null l then [] else [toRow l]
+      toHeaderRow l = [toRow l | not (null l)]
   return $ B.table (B.simpleCaption $ B.plain title)
              (zip (replicate numOfCols AlignDefault) widths)
              (TableHead nullAttr $ toHeaderRow headerRow)
@@ -906,7 +906,7 @@ csvTableDirective top fields rawcsv = do
                                $ splitTextBy (`elem` (" ," :: String)) specs
                  _ -> replicate numOfCols ColWidthDefault
          let toRow = Row nullAttr . map B.simpleCell
-             toHeaderRow l = if null l then [] else [toRow l]
+             toHeaderRow l = [toRow l | not (null l)]
          return $ B.table (B.simpleCaption $ B.plain title)
                           (zip (replicate numOfCols AlignDefault) widths)
                           (TableHead nullAttr $ toHeaderRow headerRow)
@@ -1014,7 +1014,7 @@ toChunks = dropWhile T.null
 
 codeblock :: Text -> [Text] -> [(Text, Text)] -> Text -> Text -> Bool
           -> RSTParser m Blocks
-codeblock ident classes fields lang body rmTrailingNewlines = do
+codeblock ident classes fields lang body rmTrailingNewlines =
   return $ B.codeBlockWith attribs $ stripTrailingNewlines' body
     where stripTrailingNewlines' = if rmTrailingNewlines
                                      then stripTrailingNewlines

src/Text/Pandoc/Readers/TWiki.hs

@@ -214,7 +214,7 @@ listItemLine prefix marker = mconcat <$> (lineContent >>= parseContent)
     listContinuation = notFollowedBy (textStr prefix >> marker) >>
                        string "   " >> lineContent
     parseContent = parseFromString' $ many1 $ nestedList <|> parseInline
-    parseInline = (B.plain . mconcat) <$> many1Till inline (lastNewline <|> newlineBeforeNestedList)
+    parseInline = B.plain . mconcat <$> many1Till inline (lastNewline <|> newlineBeforeNestedList)
     nestedList = list prefix
     lastNewline = try $ char '\n' <* eof
     newlineBeforeNestedList = try $ char '\n' <* lookAhead nestedList
@@ -235,7 +235,7 @@ table = try $ do
     columns rows    = replicate (columCount rows) mempty
     columCount rows = length $ head rows
     toRow           = Row nullAttr . map B.simpleCell
-    toHeaderRow l = if null l then [] else [toRow l]
+    toHeaderRow l = [toRow l | not (null l)]
 
 tableParseHeader :: PandocMonad m => TWParser m ((Alignment, ColWidth), B.Blocks)
 tableParseHeader = try $ do
@@ -265,13 +265,13 @@ tableEndOfRow :: PandocMonad m => TWParser m Char
 tableEndOfRow = lookAhead (try $ char '|' >> char '\n') >> char '|'
 
 tableColumnContent :: PandocMonad m => TWParser m a -> TWParser m B.Blocks
-tableColumnContent end = (B.plain . mconcat) <$> manyTill content (lookAhead $ try end)
+tableColumnContent end = B.plain . mconcat <$> manyTill content (lookAhead $ try end)
   where
     content = continuation <|> inline
     continuation = try $ char '\\' >> newline >> return mempty
 
 blockQuote :: PandocMonad m => TWParser m B.Blocks
-blockQuote = (B.blockQuote . mconcat) <$> parseHtmlContent "blockquote" block
+blockQuote = B.blockQuote . mconcat <$> parseHtmlContent "blockquote" block
 
 noautolink :: PandocMonad m => TWParser m B.Blocks
 noautolink = do
@@ -285,7 +285,7 @@ noautolink = do
     parseContent = parseFromString' $ many block
 
 para :: PandocMonad m => TWParser m B.Blocks
-para = (result . mconcat) <$> many1Till inline endOfParaElement
+para = result . mconcat <$> many1Till inline endOfParaElement
  where
    endOfParaElement = lookAhead $ endOfInput <|> endOfPara <|> newBlockElement
    endOfInput       = try $ skipMany blankline >> skipSpaces >> eof
@@ -428,13 +428,13 @@ nestedString end = innerSpace <|> countChar 1 nonspaceChar
     innerSpace = try $ many1Char spaceChar <* notFollowedBy end
 
 boldCode :: PandocMonad m => TWParser m B.Inlines
-boldCode = try $ (B.strong . B.code . fromEntities) <$> enclosed (string "==") nestedString
+boldCode = try $ B.strong . B.code . fromEntities <$> enclosed (string "==") nestedString
 
 htmlComment :: PandocMonad m => TWParser m B.Inlines
 htmlComment = htmlTag isCommentTag >> return mempty
 
 code :: PandocMonad m => TWParser m B.Inlines
-code = try $ (B.code . fromEntities) <$> enclosed (char '=') nestedString
+code = try $ B.code . fromEntities <$> enclosed (char '=') nestedString
 
 codeHtml :: PandocMonad m => TWParser m B.Inlines
 codeHtml = do

src/Text/Pandoc/Readers/Textile.hs

@@ -282,7 +282,7 @@ definitionListStart = try $ do
 -- break.
 definitionListItem :: PandocMonad m => ParserT Text ParserState m (Inlines, [Blocks])
 definitionListItem = try $ do
-  term <- (mconcat . intersperse B.linebreak) <$> many1 definitionListStart
+  term <- mconcat . intersperse B.linebreak <$> many1 definitionListStart
   def' <- string ":=" *> optional whitespace *> (multilineDef <|> inlineDef)
   return (term, def')
   where inlineDef :: PandocMonad m => ParserT Text ParserState m [Blocks]
@@ -378,7 +378,7 @@ table = try $ do
   let nbOfCols = maximum $ map length (headers:rows)
   let aligns = map minimum $ transpose $ map (map (snd . fst)) (headers:rows)
   let toRow = Row nullAttr . map B.simpleCell
-      toHeaderRow l = if null l then [] else [toRow l]
+      toHeaderRow l = [toRow l | not (null l)]
   return $ B.table (B.simpleCaption $ B.plain caption)
     (zip aligns (replicate nbOfCols ColWidthDefault))
     (TableHead nullAttr $ toHeaderRow $ map snd headers)
@@ -439,7 +439,7 @@ inlineParsers = [ str
                 , link
                 , image
                 , mark
-                , (B.str . T.singleton) <$> characterReference
+                , B.str . T.singleton <$> characterReference
                 , smartPunctuation inline
                 , symbol
                 ]

src/Text/Pandoc/Readers/Txt2Tags.hs

@@ -267,7 +267,7 @@ table = try $ do
   let rowsPadded = map (pad size) rows'
   let headerPadded = if null tableHeader then mempty else pad size tableHeader
   let toRow = Row nullAttr . map B.simpleCell
-      toHeaderRow l = if null l then [] else [toRow l]
+      toHeaderRow l = [toRow l | not (null l)]
   return $ B.table B.emptyCaption
                     (zip aligns (replicate ncolumns ColWidthDefault))
                       (TableHead nullAttr $ toHeaderRow headerPadded)

src/Text/Pandoc/Shared.hs

@@ -580,7 +580,7 @@ makeSections numbering mbBaseLevel bs =
     let kvs' = -- don't touch number if already present
                case lookup "number" kvs of
                   Nothing | numbering
-                          , not ("unnumbered" `elem` classes) ->
+                          , "unnumbered" `notElem` classes ->
                         ("number", T.intercalate "." (map tshow newnum)) : kvs
                   _ -> kvs
     let divattr = (ident, "section":classes, kvs')
@@ -626,11 +626,9 @@ headerLtEq _ _                   = False
 uniqueIdent :: Extensions -> [Inline] -> Set.Set T.Text -> T.Text
 uniqueIdent exts title' usedIdents =
   if baseIdent `Set.member` usedIdents
-     then case find (\x -> numIdent x `Set.notMember` usedIdents)
-               ([1..60000] :: [Int]) of
-            Just x  -> numIdent x
-            Nothing -> baseIdent
-            -- if we have more than 60,000, allow repeats
+     then maybe baseIdent numIdent
+          $ find (\x -> numIdent x `Set.notMember` usedIdents) ([1..60000] :: [Int])
+          -- if we have more than 60,000, allow repeats
      else baseIdent
   where
     baseIdent = case inlineListToIdentifier exts title' of

src/Text/Pandoc/Writers/CommonMark.hs

@@ -1,5 +1,3 @@
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE ViewPatterns      #-}
 {- |
    Module      : Text.Pandoc.Writers.CommonMark
    Copyright   : Copyright (C) 2015-2020 John MacFarlane

src/Text/Pandoc/Writers/ConTeXt.hs

@@ -209,7 +209,7 @@ blockToConTeXt (Div (ident,_,kvs) bs) = do
                                      <> literal lng <> "]" $$ txt $$ "\\stop"
                        Nothing  -> txt
       wrapBlank txt = blankline <> txt <> blankline
-  (wrapBlank . wrapLang . wrapDir . wrapRef) <$> blockListToConTeXt bs
+  wrapBlank . wrapLang . wrapDir . wrapRef <$> blockListToConTeXt bs
 blockToConTeXt (BulletList lst) = do
   contents <- mapM listItemToConTeXt lst
   return $ ("\\startitemize" <> if isTightList lst
@@ -332,7 +332,7 @@ alignToConTeXt align = case align of
                          AlignDefault -> empty
 
 listItemToConTeXt :: PandocMonad m => [Block] -> WM m (Doc Text)
-listItemToConTeXt list = (("\\item" $$) . nest 2) <$> blockListToConTeXt list
+listItemToConTeXt list = ("\\item" $$) . nest 2 <$> blockListToConTeXt list
 
 defListItemToConTeXt :: PandocMonad m => ([Inline], [[Block]]) -> WM m (Doc Text)
 defListItemToConTeXt (term, defs) = do
@@ -487,7 +487,7 @@ inlineToConTeXt (Span (_,_,kvs) ils) = do
                        Just lng -> braces ("\\language" <>
                                            brackets (literal lng) <> txt)
                        Nothing -> txt
-  (wrapLang . wrapDir) <$> inlineListToConTeXt ils
+  wrapLang . wrapDir <$> inlineListToConTeXt ils
 
 -- | Craft the section header, inserting the section reference, if supplied.
 sectionHeader :: PandocMonad m

src/Text/Pandoc/Writers/Docbook.hs

@@ -179,7 +179,7 @@ blockToDocbook opts (Div (id',"section":_,_) (Header lvl _ ils : xs)) = do
 blockToDocbook opts (Div (ident,_,_) [Para lst]) =
   let attribs = [("id", ident) | not (T.null ident)] in
   if hasLineBreaks lst
-     then (flush . nowrap . inTags False "literallayout" attribs)
+     then flush . nowrap . inTags False "literallayout" attribs
                          <$> inlinesToDocbook opts lst
      else inTags True "para" attribs <$> inlinesToDocbook opts lst
 blockToDocbook opts (Div (ident,_,_) bs) = do
@@ -206,7 +206,7 @@ blockToDocbook opts (Para [Image attr txt (src,T.stripPrefix "fig:" -> Just _)])
              (imageToDocbook opts attr src) $$
            inTagsSimple "textobject" (inTagsSimple "phrase" alt))
 blockToDocbook opts (Para lst)
-  | hasLineBreaks lst = (flush . nowrap . inTagsSimple "literallayout")
+  | hasLineBreaks lst = flush . nowrap . inTagsSimple "literallayout"
                         <$> inlinesToDocbook opts lst
   | otherwise         = inTagsIndented "para" <$> inlinesToDocbook opts lst
 blockToDocbook opts (LineBlock lns) =
@@ -277,7 +277,7 @@ blockToDocbook opts (Table _ blkCapt specs thead tbody tfoot) = do
   head' <- if all null headers
               then return empty
               else inTagsIndented "thead" <$> tableRowToDocbook opts headers
-  body' <- (inTagsIndented "tbody" . vcat) <$>
+  body' <- inTagsIndented "tbody" . vcat <$>
               mapM (tableRowToDocbook opts) rows
   return $ inTagsIndented tableType $ captionDoc $$
         inTags True "tgroup" [("cols", tshow (length aligns))] (
@@ -305,14 +305,14 @@ tableRowToDocbook :: PandocMonad m
                   -> [[Block]]
                   -> DB m (Doc Text)
 tableRowToDocbook opts cols =
-  (inTagsIndented "row" . vcat) <$> mapM (tableItemToDocbook opts) cols
+  inTagsIndented "row" . vcat <$> mapM (tableItemToDocbook opts) cols
 
 tableItemToDocbook :: PandocMonad m
                    => WriterOptions
                    -> [Block]
                    -> DB m (Doc Text)
 tableItemToDocbook opts item =
-  (inTags True "entry" [] . vcat) <$> mapM (blockToDocbook opts) item
+  inTags True "entry" [] . vcat <$> mapM (blockToDocbook opts) item
 
 -- | Convert a list of inline elements to Docbook.
 inlinesToDocbook :: PandocMonad m => WriterOptions -> [Inline] -> DB m (Doc Text)

src/Text/Pandoc/Writers/Docx.hs

@@ -1030,7 +1030,7 @@ blockToOpenXML' opts (Table _ blkCapt specs thead tbody tfoot) = do
   let rowwidth = fullrow * sum widths
   let mkgridcol w = mknode "w:gridCol"
                        [("w:w", show (floor (textwidth * w) :: Integer))] ()
-  let hasHeader = any (not . null) headers
+  let hasHeader = not $ all null headers
   modify $ \s -> s { stInTable = False }
   return $
     caption' ++

src/Text/Pandoc/Writers/EPUB.hs

@@ -62,7 +62,7 @@ import Text.DocTemplates (FromContext(lookupContext), Context(..),
                           ToContext(toVal), Val(..))
 
 -- A Chapter includes a list of blocks.
-data Chapter = Chapter [Block]
+newtype Chapter = Chapter [Block]
   deriving (Show)
 
 data EPUBState = EPUBState {
@@ -711,10 +711,10 @@ pandocToEPUB version opts doc = do
                          | writerTableOfContents opts ] ++
                   map chapterRefNode chapterEntries)
           , unode "guide" $
-             [ unode "reference" !
-                   [("type","toc"),("title", tocTitle),
-                    ("href","nav.xhtml")] $ ()
-             ] ++
+             (unode "reference" !
+                 [("type","toc"),("title", tocTitle),
+                  ("href","nav.xhtml")] $ ()
+             ) :
              [ unode "reference" !
                    [("type","cover")
                    ,("title","Cover")
@@ -838,14 +838,12 @@ pandocToEPUB version opts doc = do
                                 ] | writerTableOfContents opts
                               ]
                          else []
-  let landmarks = if null landmarkItems
-                     then []
-                     else [RawBlock (Format "html") $ TS.pack $ ppElement $
-                            unode "nav" ! [("epub:type","landmarks")
-                                          ,("id","landmarks")
-                                          ,("hidden","hidden")] $
-                            [ unode "ol" landmarkItems ]
-                          ]
+  let landmarks = [RawBlock (Format "html") $ TS.pack $ ppElement $
+                    unode "nav" ! [("epub:type","landmarks")
+                                  ,("id","landmarks")
+                                  ,("hidden","hidden")] $
+                    [ unode "ol" landmarkItems ]
+                  | not (null landmarkItems)]
   navData <- lift $ writeHtml opts'{ writerVariables =
                      Context (M.fromList [("navpage", toVal' "true")])
                      <> cssvars False <> vars }
@@ -940,7 +938,7 @@ metadataElement version md currentTime =
           | version == EPUB2 = [dcNode "identifier" !
               (("id",id') : maybe [] (\x -> [("opf:scheme", x)]) scheme) $
               txt]
-          | otherwise = [dcNode "identifier" ! [("id",id')] $ txt] ++
+          | otherwise = (dcNode "identifier" ! [("id",id')] $ txt) :
               maybe [] ((\x -> [unode "meta" !
                                 [ ("refines",'#':id')
                                 , ("property","identifier-type")

src/Text/Pandoc/Writers/HTML.hs

@@ -1,4 +1,3 @@
-{-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE LambdaCase          #-}
 {-# LANGUAGE MultiWayIf          #-}
 {-# LANGUAGE OverloadedStrings   #-}
@@ -1025,7 +1024,7 @@ rowListToHtml :: PandocMonad m
               -> [TableRow]
               -> StateT WriterState m Html
 rowListToHtml opts rows =
-  (\x -> (nl opts *> mconcat x)) <$>
+  (\x -> nl opts *> mconcat x) <$>
      mapM (tableRowToHtml opts) rows
 
 colSpecListToHtml :: PandocMonad m

src/Text/Pandoc/Writers/Haddock.hs

@@ -28,7 +28,7 @@ import Text.Pandoc.Templates (renderTemplate)
 import Text.Pandoc.Writers.Shared
 
 type Notes = [[Block]]
-data WriterState = WriterState { stNotes :: Notes }
+newtype WriterState = WriterState { stNotes :: Notes }
 instance Default WriterState
   where def = WriterState{ stNotes = [] }
 

src/Text/Pandoc/Writers/JATS.hs

@@ -216,7 +216,7 @@ imageMimeType src kvs =
                   (T.takeWhile (/='/') <$> mbMT)
       subtype = fromMaybe "" $
                   lookup "mime-subtype" kvs `mplus`
-                  ((T.drop 1 . T.dropWhile (/='/')) <$> mbMT)
+                  (T.drop 1 . T.dropWhile (/='/') <$> mbMT)
   in (maintype, subtype)
 
 languageFor :: [Text] -> Text
@@ -372,7 +372,7 @@ blockToJATS opts (Table _ blkCapt specs th tb tf) =
       thead <- if all null headers
                   then return empty
                   else inTagsIndented "thead" <$> tableRowToJATS opts True headers
-      tbody <- (inTagsIndented "tbody" . vcat) <$>
+      tbody <- inTagsIndented "tbody" . vcat <$>
                     mapM (tableRowToJATS opts False) rows
       return $ inTags True "table" [] $ coltags $$ thead $$ tbody
 
@@ -389,7 +389,7 @@ tableRowToJATS :: PandocMonad m
                   -> [[Block]]
                   -> JATS m (Doc Text)
 tableRowToJATS opts isHeader cols =
-  (inTagsIndented "tr" . vcat) <$> mapM (tableItemToJATS opts isHeader) cols
+  inTagsIndented "tr" . vcat <$> mapM (tableItemToJATS opts isHeader) cols
 
 tableItemToJATS :: PandocMonad m
                    => WriterOptions
@@ -400,7 +400,7 @@ tableItemToJATS opts isHeader [Plain item] =
   inTags False (if isHeader then "th" else "td") [] <$>
     inlinesToJATS opts item
 tableItemToJATS opts isHeader item =
-  (inTags False (if isHeader then "th" else "td") [] . vcat) <$>
+  inTags False (if isHeader then "th" else "td") [] . vcat <$>
     mapM (blockToJATS opts) item
 
 -- | Convert a list of inline elements to JATS.
@@ -547,7 +547,7 @@ inlineToJATS _ (Image (ident,_,kvs) _ (src, tit)) = do
                   (T.takeWhile (/='/') <$> mbMT)
   let subtype = fromMaybe "" $
                   lookup "mime-subtype" kvs `mplus`
-                  ((T.drop 1 . T.dropWhile (/='/')) <$> mbMT)
+                  (T.drop 1 . T.dropWhile (/='/') <$> mbMT)
   let attr = [("id", ident) | not (T.null ident)] ++
              [("mimetype", maintype),
               ("mime-subtype", subtype),

src/Text/Pandoc/Writers/LaTeX.hs

@@ -1049,7 +1049,7 @@ wrapDiv (_,classes,kvs) t = do
                            let valign = maybe "T" mapAlignment (lookup "align" kvs)
                                totalwidth = maybe [] (\x -> ["totalwidth=" <> x])
                                  (lookup "totalwidth" kvs)
-                               onlytextwidth = filter ((==) "onlytextwidth") classes
+                               onlytextwidth = filter ("onlytextwidth" ==) classes
                                options = text $ T.unpack $ T.intercalate "," $
                                  valign : totalwidth ++ onlytextwidth 
                            in inCmd "begin" "columns" <> brackets options
@@ -1458,8 +1458,8 @@ citeArgumentsList (CiteGroup _ _ []) = return empty
 citeArgumentsList (CiteGroup pfxs sfxs ids) = do
       pdoc <- inlineListToLaTeX pfxs
       sdoc <- inlineListToLaTeX sfxs'
-      return $ (optargs pdoc sdoc) <>
-              (braces (literal (T.intercalate "," (reverse ids))))
+      return $ optargs pdoc sdoc <>
+              braces (literal (T.intercalate "," (reverse ids)))
       where sfxs' = stripLocatorBraces $ case sfxs of
                 (Str t : r) -> case T.uncons t of
                   Just (x, xs)
@@ -1516,12 +1516,12 @@ citationsToBiblatex (c:cs)
 
       groups <- mapM citeArgumentsList (reverse (foldl' grouper [] (c:cs)))
 
-      return $ text cmd <> (mconcat groups)
+      return $ text cmd <> mconcat groups
 
   where grouper prev cit = case prev of
          ((CiteGroup oPfx oSfx ids):rest)
-             | null oSfx && null pfx -> (CiteGroup oPfx sfx (cid:ids)):rest
-         _ -> (CiteGroup pfx sfx [cid]):prev
+             | null oSfx && null pfx -> CiteGroup oPfx sfx (cid:ids) : rest
+         _ -> CiteGroup pfx sfx [cid] : prev
          where pfx = citationPrefix cit
                sfx = citationSuffix cit
                cid = citationId cit

src/Text/Pandoc/Writers/Man.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE LambdaCase        #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ViewPatterns      #-}
 {- |
@@ -232,8 +233,7 @@ definitionListItemToMan opts (label, defs) = do
   labelText <- inlineListToMan opts $ makeCodeBold label
   contents <- if null defs
                  then return empty
-                 else liftM vcat $ forM defs $ \blocks ->
-                        case blocks of
+                 else liftM vcat $ forM defs $ \case
                           (x:xs) -> do
                             first' <- blockToMan opts $
                                       case x of

src/Text/Pandoc/Writers/Markdown.hs

@@ -24,10 +24,9 @@ import Control.Monad.Reader
 import Control.Monad.State.Strict
 import Data.Char (isAlphaNum)
 import Data.Default
-import Data.List (find, intersperse, sortBy, transpose)
+import Data.List (find, intersperse, sortOn, transpose)
 import qualified Data.Map as M
 import Data.Maybe (fromMaybe, mapMaybe)
-import Data.Ord (comparing)
 import qualified Data.Set as Set
 import Data.Text (Text)
 import qualified Data.Text as T
@@ -127,7 +126,7 @@ pandocTitleBlock tit auths dat =
 
 mmdTitleBlock :: Context Text -> Doc Text
 mmdTitleBlock (Context hashmap) =
-  vcat $ map go $ sortBy (comparing fst) $ M.toList hashmap
+  vcat $ map go $ sortOn fst $ M.toList hashmap
   where go (k,v) =
           case (text (T.unpack k), v) of
                (k', ListVal xs)
@@ -148,15 +147,15 @@ mmdTitleBlock (Context hashmap) =
 plainTitleBlock :: Doc Text -> [Doc Text] -> Doc Text -> Doc Text
 plainTitleBlock tit auths dat =
   tit <> cr <>
-  (hcat (intersperse (text "; ") auths)) <> cr <>
+  hcat (intersperse (text "; ") auths) <> cr <>
   dat <> cr
 
 yamlMetadataBlock :: Context Text -> Doc Text
-yamlMetadataBlock v = "---" $$ (contextToYaml v) $$ "---"
+yamlMetadataBlock v = "---" $$ contextToYaml v $$ "---"
 
 contextToYaml :: Context Text -> Doc Text
 contextToYaml (Context o) =
-  vcat $ map keyvalToYaml $ sortBy (comparing fst) $ M.toList o
+  vcat $ map keyvalToYaml $ sortOn fst $ M.toList o
  where
   keyvalToYaml (k,v) =
           case (text (T.unpack k), v) of
@@ -250,7 +249,7 @@ pandocToMarkdown opts (Pandoc meta blocks) = do
 
 -- | Return markdown representation of reference key table.
 refsToMarkdown :: PandocMonad m => WriterOptions -> Refs -> MD m (Doc Text)
-refsToMarkdown opts refs = mapM (keyToMarkdown opts) refs >>= return . vcat
+refsToMarkdown opts refs = vcat <$> mapM (keyToMarkdown opts) refs
 
 -- | Return markdown representation of a reference key.
 keyToMarkdown :: PandocMonad m
@@ -446,7 +445,7 @@ blockToMarkdown' opts (Plain inlines) = do
            then inlines
            else case inlines of
                   (Str t:ys)
-                    | (null ys || startsWithSpace ys)
+                    | null ys || startsWithSpace ys
                     , beginsWithOrderedListMarker t
                     -> RawInline (Format "markdown") (escapeMarker t):ys
                   (Str t:_)
@@ -462,7 +461,7 @@ blockToMarkdown' opts (Para [Image attr alt (src,tgt@(T.stripPrefix "fig:" -> Ju
   | isEnabled Ext_raw_html opts &&
     not (isEnabled Ext_link_attributes opts) &&
     attr /= nullAttr = -- use raw HTML
-    ((<> blankline) . literal . T.strip) <$>
+    (<> blankline) . literal . T.strip <$>
       writeHtml5String opts{ writerTemplate = Nothing }
         (Pandoc nullMeta [Para [Image attr alt (src,tgt)]])
   | otherwise = blockToMarkdown opts (Para [Image attr alt (src,tit)])
@@ -472,7 +471,7 @@ blockToMarkdown' opts (LineBlock lns) =
   if isEnabled Ext_line_blocks opts
   then do
     mdLines <- mapM (inlineListToMarkdown opts) lns
-    return $ (vcat $ map (hang 2 (literal "| ")) mdLines) <> blankline
+    return $ vcat (map (hang 2 (literal "| ")) mdLines) <> blankline
   else blockToMarkdown opts $ linesToPara lns
 blockToMarkdown' opts b@(RawBlock f str) = do
   variant <- asks envVariant
@@ -582,28 +581,28 @@ blockToMarkdown' opts (CodeBlock attribs str) = do
          attrs  = if isEnabled Ext_fenced_code_attributes opts
                      then nowrap $ " " <> attrsToMarkdown attribs
                      else case attribs of
-                                (_,(cls:_),_) -> " " <> literal cls
+                                (_,cls:_,_) -> " " <> literal cls
                                 _             -> empty
 blockToMarkdown' opts (BlockQuote blocks) = do
   variant <- asks envVariant
   -- if we're writing literate haskell, put a space before the bird tracks
   -- so they won't be interpreted as lhs...
-  let leader = if isEnabled Ext_literate_haskell opts
-                  then " > "
-                  else if variant == PlainText then "  " else "> "
+  let leader
+        | isEnabled Ext_literate_haskell opts = " > "
+        | variant == PlainText = "  "
+        | otherwise            = "> "
   contents <- blockListToMarkdown opts blocks
-  return $ (prefixed leader contents) <> blankline
+  return $ prefixed leader contents <> blankline
 blockToMarkdown' opts t@(Table _ blkCapt specs thead tbody tfoot) = do
   let (caption, aligns, widths, headers, rows) = toLegacyTable blkCapt specs thead tbody tfoot
   let numcols = maximum (length aligns : length widths :
                            map length (headers:rows))
   caption' <- inlineListToMarkdown opts caption
-  let caption'' = if null caption
-                     then blankline
-                     else
-                       if isEnabled Ext_table_captions opts
-                          then blankline $$ (": " <> caption') $$ blankline
-                          else blankline $$ caption' $$ blankline
+  let caption''
+        | null caption = blankline
+        | isEnabled Ext_table_captions opts
+        = blankline $$ (": " <> caption') $$ blankline
+        | otherwise = blankline $$ caption' $$ blankline
   let hasSimpleCells = onlySimpleTableCells $ headers : rows
   let isSimple = hasSimpleCells && all (==0) widths
   let isPlainBlock (Plain _) = True
@@ -652,7 +651,7 @@ blockToMarkdown' opts t@(Table _ blkCapt specs thead tbody tfoot) = do
                 (id,) <$> pipeTable (all null headers) aligns' rawHeaders rawRows
             | isEnabled Ext_raw_html opts -> fmap (id,) $
                    literal <$>
-                   (writeHtml5String opts{ writerTemplate = Nothing } $ Pandoc nullMeta [t])
+                   writeHtml5String opts{ writerTemplate = Nothing } (Pandoc nullMeta [t])
             | otherwise -> return (id, literal "[TABLE]")
   return $ nst (tbl $$ caption'') $$ blankline
 blockToMarkdown' opts (BulletList items) = do
@@ -680,7 +679,7 @@ inList p = local (\env -> env {envInList = True}) p
 addMarkdownAttribute :: Text -> Text
 addMarkdownAttribute s =
   case span isTagText $ reverse $ parseTags s of
-       (xs,(TagOpen t attrs:rest)) ->
+       (xs, TagOpen t attrs:rest) ->
             renderTags' $ reverse rest ++ (TagOpen t attrs' : reverse xs)
               where attrs' = ("markdown","1"):[(x,y) | (x,y) <- attrs,
                                  x /= "markdown"]
@@ -745,17 +744,16 @@ pandocTable opts multiline headless aligns widths rawHeaders rawRows = do
         | isSimple  = map numChars columns
         | otherwise = zipWith relWidth widths columns
   let makeRow = hcat . intersperse (lblock 1 (literal " ")) .
-                   (zipWith3 alignHeader aligns widthsInChars)
+                   zipWith3 alignHeader aligns widthsInChars
   let rows' = map makeRow rawRows
   let head' = makeRow rawHeaders
   let underline = mconcat $ intersperse (literal " ") $
                   map (\width -> literal (T.replicate width "-")) widthsInChars
-  let border = if multiline
-                  then literal (T.replicate (sum widthsInChars +
-                          length widthsInChars - 1) "-")
-                  else if headless
-                          then underline
-                          else empty
+  let border
+        | multiline = literal (T.replicate (sum widthsInChars +
+                        length widthsInChars - 1) "-")
+        | headless  = underline
+        | otherwise = empty
   let head'' = if headless
                   then empty
                   else border <> cr <> head'
@@ -890,18 +888,17 @@ blockListToMarkdown opts blocks = do
       isListBlock (OrderedList _ _)  = True
       isListBlock (DefinitionList _) = True
       isListBlock _                  = False
-      commentSep  = if variant == PlainText
-                       then Null
-                       else if isEnabled Ext_raw_html opts
-                            then RawBlock "html" "<!-- -->\n"
-                            else RawBlock "markdown" "&nbsp;\n"
-  mapM (blockToMarkdown opts) (fixBlocks blocks) >>= return . mconcat
+      commentSep
+        | variant == PlainText        = Null
+        | isEnabled Ext_raw_html opts = RawBlock "html" "<!-- -->\n"
+        | otherwise                   = RawBlock "markdown" "&nbsp;\n"
+  mconcat <$> mapM (blockToMarkdown opts) (fixBlocks blocks)
 
 getKey :: Doc Text -> Key
 getKey = toKey . render Nothing
 
 findUsableIndex :: [Text] -> Int -> Int
-findUsableIndex lbls i = if (tshow i) `elem` lbls
+findUsableIndex lbls i = if tshow i `elem` lbls
                          then findUsableIndex lbls (i + 1)
                          else i
 
@@ -973,19 +970,19 @@ inlineListToMarkdown opts lst = do
   go (if inlist then avoidBadWrapsInList lst else lst)
   where go [] = return empty
         go (i:is) = case i of
-            (Link _ _ _) -> case is of
+            Link {} -> case is of
                 -- If a link is followed by another link, or '[', '(' or ':'
                 -- then we don't shortcut
-                (Link _ _ _):_                                  -> unshortcutable
-                Space:(Link _ _ _):_                            -> unshortcutable
+                Link {}:_                                       -> unshortcutable
+                Space:Link {}:_                                 -> unshortcutable
                 Space:(Str(thead -> Just '[')):_                -> unshortcutable
                 Space:(RawInline _ (thead -> Just '[')):_       -> unshortcutable
                 Space:(Cite _ _):_                              -> unshortcutable
-                SoftBreak:(Link _ _ _):_                        -> unshortcutable
+                SoftBreak:Link {}:_                             -> unshortcutable
                 SoftBreak:(Str(thead -> Just '[')):_            -> unshortcutable
                 SoftBreak:(RawInline _ (thead -> Just '[')):_   -> unshortcutable
                 SoftBreak:(Cite _ _):_                          -> unshortcutable
-                LineBreak:(Link _ _ _):_                        -> unshortcutable
+                LineBreak:Link {}:_                             -> unshortcutable
                 LineBreak:(Str(thead -> Just '[')):_            -> unshortcutable
                 LineBreak:(RawInline _ (thead -> Just '[')):_   -> unshortcutable
                 LineBreak:(Cite _ _):_                          -> unshortcutable
@@ -1016,16 +1013,16 @@ avoidBadWrapsInList :: [Inline] -> [Inline]
 avoidBadWrapsInList [] = []
 avoidBadWrapsInList (s:Str (T.uncons -> Just ('>',cs)):xs) | isSp s =
   Str (" >" <> cs) : avoidBadWrapsInList xs
-avoidBadWrapsInList (s:Str (T.uncons -> Just (c, cs)):[])
-  | T.null cs && isSp s && c `elem` ['-','*','+'] = Str (T.pack [' ', c]) : []
+avoidBadWrapsInList [s, Str (T.uncons -> Just (c, cs))]
+  | T.null cs && isSp s && c `elem` ['-','*','+'] = [Str $ T.pack [' ', c]]
 avoidBadWrapsInList (s:Str (T.uncons -> Just (c, cs)):Space:xs)
   | T.null cs && isSp s && c `elem` ['-','*','+'] =
     Str (T.pack [' ', c]) : Space : avoidBadWrapsInList xs
 avoidBadWrapsInList (s:Str cs:Space:xs)
   | isSp s && isOrderedListMarker cs =
     Str (" " <> cs) : Space : avoidBadWrapsInList xs
-avoidBadWrapsInList (s:Str cs:[])
-  | isSp s && isOrderedListMarker cs = Str (" " <> cs) : []
+avoidBadWrapsInList [s, Str cs]
+  | isSp s && isOrderedListMarker cs = [Str $ " " <> cs]
 avoidBadWrapsInList (x:xs) = x : avoidBadWrapsInList xs
 
 isOrderedListMarker :: Text -> Bool
@@ -1105,7 +1102,7 @@ inlineToMarkdown opts (Strikeout lst) = do
                        else contents
 inlineToMarkdown _ (Superscript []) = return empty
 inlineToMarkdown opts (Superscript lst) =
-  local (\env -> env {envEscapeSpaces = (envVariant env == Markdown)}) $ do
+  local (\env -> env {envEscapeSpaces = envVariant env == Markdown}) $ do
     contents <- inlineListToMarkdown opts lst
     if isEnabled Ext_superscript opts
        then return $ "^" <> contents <> "^"
@@ -1123,7 +1120,7 @@ inlineToMarkdown opts (Superscript lst) =
                            Nothing -> literal $ "^(" <> rendered <> ")"
 inlineToMarkdown _ (Subscript []) = return empty
 inlineToMarkdown opts (Subscript lst) =
-  local (\env -> env {envEscapeSpaces = (envVariant env == Markdown)}) $ do
+  local (\env -> env {envEscapeSpaces = envVariant env == Markdown}) $ do
     contents <- inlineListToMarkdown opts lst
     if isEnabled Ext_subscript opts
        then return $ "~" <> contents <> "~"
@@ -1167,7 +1164,7 @@ inlineToMarkdown opts (Code attr str) = do
                      then 0
                      else maximum $ map T.length tickGroups
   let marker     = T.replicate (longest + 1) "`"
-  let spacer     = if (longest == 0) then "" else " "
+  let spacer     = if longest == 0 then "" else " "
   let attrs      = if isEnabled Ext_inline_code_attributes opts && attr /= nullAttr
                       then attrsToMarkdown attr
                       else empty
@@ -1296,7 +1293,7 @@ inlineToMarkdown opts lnk@(Link attr txt (src, tit))
   | isEnabled Ext_raw_html opts &&
     not (isEnabled Ext_link_attributes opts) &&
     attr /= nullAttr = -- use raw HTML
-    (literal . T.strip) <$>
+    literal . T.strip <$>
       writeHtml5String opts{ writerTemplate = Nothing } (Pandoc nullMeta [Plain [lnk]])
   | otherwise = do
   variant <- asks envVariant
@@ -1337,7 +1334,7 @@ inlineToMarkdown opts img@(Image attr alternate (source, tit))
   | isEnabled Ext_raw_html opts &&
     not (isEnabled Ext_link_attributes opts) &&
     attr /= nullAttr = -- use raw HTML
-    (literal . T.strip) <$>
+    literal . T.strip <$>
       writeHtml5String opts{ writerTemplate = Nothing } (Pandoc nullMeta [Plain [img]])
   | otherwise = do
   variant <- asks envVariant
@@ -1352,7 +1349,7 @@ inlineToMarkdown opts img@(Image attr alternate (source, tit))
 inlineToMarkdown opts (Note contents) = do
   modify (\st -> st{ stNotes = contents : stNotes st })
   st <- get
-  let ref = literal $ writerIdentifierPrefix opts <> tshow (stNoteNum st + (length $ stNotes st) - 1)
+  let ref = literal $ writerIdentifierPrefix opts <> tshow (stNoteNum st + length (stNotes st) - 1)
   if isEnabled Ext_footnotes opts
      then return $ "[^" <> ref <> "]"
      else return $ "[" <> ref <> "]"

src/Text/Pandoc/Writers/Ms.hs

@@ -67,9 +67,7 @@ pandocToMs opts (Pandoc meta blocks) = do
   let authorsMeta = map (escapeStr opts . stringify) $ docAuthors meta
   hasHighlighting <- gets stHighlighting
   let highlightingMacros = if hasHighlighting
-                              then case writerHighlightStyle opts of
-                                        Nothing  -> mempty
-                                        Just sty -> styleToMs sty
+                              then maybe mempty styleToMs $ writerHighlightStyle opts
                               else mempty
 
   let context = defField "body" main
@@ -523,7 +521,7 @@ msFormatter opts _fmtopts =
  where
   fmtLine = mconcat . map fmtToken
   fmtToken (toktype, tok) =
-    "\\*[" <> (tshow toktype) <> " \"" <> (escapeStr opts tok) <> "\"]"
+    "\\*[" <> tshow toktype <> " \"" <> escapeStr opts tok <> "\"]"
 
 highlightCode :: PandocMonad m => WriterOptions -> Attr -> Text -> MS m (Doc Text)
 highlightCode opts attr str =

src/Text/Pandoc/Writers/ODT.hs

@@ -71,7 +71,7 @@ pandocToODT opts doc@(Pandoc meta _) = do
   refArchive <-
        case writerReferenceDoc opts of
              Just f -> liftM toArchive $ lift $ P.readFileLazy f
-             Nothing -> lift $ (toArchive . B.fromStrict) <$>
+             Nothing -> lift $ toArchive . B.fromStrict <$>
                                 P.readDataFile "reference.odt"
   -- handle formulas and pictures
   -- picEntriesRef <- P.newIORef ([] :: [Entry])

src/Text/Pandoc/Writers/OPML.hs

@@ -40,7 +40,7 @@ writeOPML opts (Pandoc meta blocks) = do
                 writeMarkdown def (Pandoc nullMeta [Plain ils]))
               meta'
   let blocks' = makeSections False (Just 1) blocks
-  main <- (render colwidth . vcat) <$>
+  main <- render colwidth . vcat <$>
              mapM (blockToOPML opts) blocks'
   let context = defField "body" main metadata
   return $

src/Text/Pandoc/Writers/OpenDocument.hs

@@ -387,7 +387,7 @@ blockToOpenDocument o bs
                            r <- vcat  <$> mapM (deflistItemToOpenDocument o) b
                            setInDefinitionList False
                            return r
-      preformatted  s = (flush . vcat) <$> mapM (inPreformattedTags . escapeStringForXML) (T.lines s)
+      preformatted  s = flush . vcat <$> mapM (inPreformattedTags . escapeStringForXML) (T.lines s)
       mkBlockQuote  b = do increaseIndent
                            i <- paraStyle
                                  [("style:parent-style-name","Quotations")]

src/Text/Pandoc/Writers/Powerpoint/Output.hs

@@ -303,11 +303,11 @@ makeSpeakerNotesMap (Presentation _ slides) =
 
 presentationToArchive :: PandocMonad m => WriterOptions -> Presentation -> m Archive
 presentationToArchive opts pres = do
-  distArchive <- (toArchive . BL.fromStrict) <$>
+  distArchive <- toArchive . BL.fromStrict <$>
                       P.readDefaultDataFile "reference.pptx"
   refArchive <- case writerReferenceDoc opts of
                      Just f  -> toArchive <$> P.readFileLazy f
-                     Nothing -> (toArchive . BL.fromStrict) <$>
+                     Nothing -> toArchive . BL.fromStrict <$>
                         P.readDataFile "reference.pptx"
 
   utctime <- P.getCurrentTime
@@ -351,10 +351,10 @@ curSlideHasSpeakerNotes =
 getLayout :: PandocMonad m => Layout -> P m Element
 getLayout layout = do
   let layoutpath = case layout of
-        (MetadataSlide{}) -> "ppt/slideLayouts/slideLayout1.xml"
-        (TitleSlide _)          -> "ppt/slideLayouts/slideLayout3.xml"
-        (ContentSlide _ _)      -> "ppt/slideLayouts/slideLayout2.xml"
-        (TwoColumnSlide{})    -> "ppt/slideLayouts/slideLayout4.xml"
+        MetadataSlide{}  -> "ppt/slideLayouts/slideLayout1.xml"
+        TitleSlide{}     -> "ppt/slideLayouts/slideLayout3.xml"
+        ContentSlide{}   -> "ppt/slideLayouts/slideLayout2.xml"
+        TwoColumnSlide{} -> "ppt/slideLayouts/slideLayout4.xml"
   refArchive <- asks envRefArchive
   distArchive <- asks envDistArchive
   parseXml refArchive distArchive layoutpath
@@ -547,7 +547,7 @@ registerMedia fp caption = do
 
 makeMediaEntry :: PandocMonad m => MediaInfo -> P m Entry
 makeMediaEntry mInfo = do
-  epochtime <- (floor . utcTimeToPOSIXSeconds) <$> asks envUTCTime
+  epochtime <- floor . utcTimeToPOSIXSeconds <$> asks envUTCTime
   (imgBytes, _) <- P.fetchItem (T.pack $ mInfoFilePath mInfo)
   let ext = fromMaybe "" (mInfoExt mInfo)
   let fp = "ppt/media/image" <>
@@ -1473,7 +1473,7 @@ presentationToRelsEntry pres = do
 
 elemToEntry :: PandocMonad m => FilePath -> Element -> P m Entry
 elemToEntry fp element = do
-  epochtime <- (floor . utcTimeToPOSIXSeconds) <$> asks envUTCTime
+  epochtime <- floor . utcTimeToPOSIXSeconds <$> asks envUTCTime
   return $ toEntry fp epochtime $ renderXml element
 
 slideToEntry :: PandocMonad m => Slide -> P m Entry
@@ -1500,8 +1500,7 @@ slideToSpeakerNotesEntry slide = do
 
 slideToSpeakerNotesRelElement :: PandocMonad m => Slide -> P m (Maybe Element)
 slideToSpeakerNotesRelElement (Slide _ _ (SpeakerNotes [])) = return Nothing
-slideToSpeakerNotesRelElement slide@(
-  Slide{}) = do
+slideToSpeakerNotesRelElement slide@Slide{} = do
   idNum <- slideNum slide
   return $ Just $
     mknode "Relationships"
@@ -1585,10 +1584,10 @@ slideToSlideRelElement :: PandocMonad m => Slide -> P m Element
 slideToSlideRelElement slide = do
   idNum <- slideNum slide
   let target =  case slide of
-        (Slide _ (MetadataSlide{}) _) -> "../slideLayouts/slideLayout1.xml"
-        (Slide _ (TitleSlide _) _)          -> "../slideLayouts/slideLayout3.xml"
-        (Slide _ (ContentSlide _ _) _)      -> "../slideLayouts/slideLayout2.xml"
-        (Slide _ (TwoColumnSlide{}) _)  -> "../slideLayouts/slideLayout4.xml"
+        (Slide _ MetadataSlide{} _)  -> "../slideLayouts/slideLayout1.xml"
+        (Slide _ TitleSlide{} _)     -> "../slideLayouts/slideLayout3.xml"
+        (Slide _ ContentSlide{} _)   -> "../slideLayouts/slideLayout2.xml"
+        (Slide _ TwoColumnSlide{} _) -> "../slideLayouts/slideLayout4.xml"
 
   speakerNotesRels <- maybeToList <$> speakerNotesSlideRelElement slide
 
@@ -1819,7 +1818,7 @@ getSpeakerNotesFilePaths = do
 
 presentationToContentTypes :: PandocMonad m => Presentation -> P m ContentTypes
 presentationToContentTypes p@(Presentation _ slides) = do
-  mediaInfos <- (mconcat . M.elems) <$> gets stMediaIds
+  mediaInfos <- mconcat . M.elems <$> gets stMediaIds
   filePaths <- patternsToFilePaths $ inheritedPatterns p
   let mediaFps = filter (match (compile "ppt/media/image*")) filePaths
   let defaults = [ DefaultContentType "xml" "application/xml"

src/Text/Pandoc/Writers/Powerpoint/Presentation.hs

@@ -537,10 +537,10 @@ withAttr _ sp = sp
 blockToShape :: Block -> Pres Shape
 blockToShape (Plain ils) = blockToShape (Para ils)
 blockToShape (Para (il:_))  | Image attr ils (url, _) <- il =
-      (withAttr attr . Pic def (T.unpack url)) <$> inlinesToParElems ils
+      withAttr attr . Pic def (T.unpack url) <$> inlinesToParElems ils
 blockToShape (Para (il:_))  | Link _ (il':_) target <- il
                             , Image attr ils (url, _) <- il' =
-      (withAttr attr . Pic def{picPropLink = Just $ ExternalTarget target} (T.unpack url))
+      withAttr attr . Pic def{picPropLink = Just $ ExternalTarget target} (T.unpack url)
       <$> inlinesToParElems ils
 blockToShape (Table _ blkCapt specs thead tbody tfoot) = do
   let (caption, algn, _, hdrCells, rows) = toLegacyTable blkCapt specs thead tbody tfoot
@@ -721,7 +721,7 @@ makeNoteEntry (n, blks) =
   let enum = Str (tshow n <> ".")
   in
     case blks of
-      (Para ils : blks') -> (Para $ enum : Space : ils) : blks'
+      (Para ils : blks') -> Para (enum : Space : ils) : blks'
       _ -> Para [enum] : blks
 
 forceFontSize :: Pixels -> Pres a -> Pres a
@@ -767,7 +767,7 @@ getMetaSlide  = do
          mempty
 
 addSpeakerNotesToMetaSlide :: Slide -> [Block] -> Pres (Slide, [Block])
-addSpeakerNotesToMetaSlide (Slide sldId layout@(MetadataSlide{}) spkNotes) blks =
+addSpeakerNotesToMetaSlide (Slide sldId layout@MetadataSlide{} spkNotes) blks =
   do let (ntsBlks, blks') = span isNotesDiv blks
      spkNotes' <- mconcat <$> mapM blockToSpeakerNotes ntsBlks
      return (Slide sldId layout (spkNotes <> spkNotes'), blks')

src/Text/Pandoc/Writers/RTF.hs

@@ -241,12 +241,12 @@ blockToRTF _ _ b@(RawBlock f str)
   | otherwise         = do
       report $ BlockNotRendered b
       return ""
-blockToRTF indent alignment (BulletList lst) = (spaceAtEnd . T.concat) <$>
+blockToRTF indent alignment (BulletList lst) = spaceAtEnd . T.concat <$>
   mapM (listItemToRTF alignment indent (bulletMarker indent)) lst
 blockToRTF indent alignment (OrderedList attribs lst) =
-  (spaceAtEnd . T.concat) <$>
+  spaceAtEnd . T.concat <$>
    zipWithM (listItemToRTF alignment indent) (orderedMarkers indent attribs) lst
-blockToRTF indent alignment (DefinitionList lst) = (spaceAtEnd . T.concat) <$>
+blockToRTF indent alignment (DefinitionList lst) = spaceAtEnd . T.concat <$>
   mapM (definitionListItemToRTF alignment indent) lst
 blockToRTF indent _ HorizontalRule = return $
   rtfPar indent 0 AlignCenter "\\emdash\\emdash\\emdash\\emdash\\emdash"

src/Text/Pandoc/Writers/TEI.hs

@@ -205,14 +205,14 @@ tableRowToTEI :: PandocMonad m
               -> [[Block]]
               -> m (Doc Text)
 tableRowToTEI opts cols =
-  (inTagsIndented "row" . vcat) <$> mapM (tableItemToTEI opts) cols
+  inTagsIndented "row" . vcat <$> mapM (tableItemToTEI opts) cols
 
 tableHeadersToTEI :: PandocMonad m
                   => WriterOptions
                   -> [[Block]]
                   -> m (Doc Text)
 tableHeadersToTEI opts cols =
-  (inTags True "row" [("role","label")] . vcat) <$>
+  inTags True "row" [("role","label")] . vcat <$>
     mapM (tableItemToTEI opts) cols
 
 tableItemToTEI :: PandocMonad m
@@ -220,7 +220,7 @@ tableItemToTEI :: PandocMonad m
                -> [Block]
                -> m (Doc Text)
 tableItemToTEI opts item =
-  (inTags False "cell" [] . vcat) <$> mapM (blockToTEI opts) item
+  inTags False "cell" [] . vcat <$> mapM (blockToTEI opts) item
 
 -- | Convert a list of inline elements to TEI.
 inlinesToTEI :: PandocMonad m => WriterOptions -> [Inline] -> m (Doc Text)

src/Text/Pandoc/Writers/XWiki.hs

@@ -45,7 +45,7 @@ import Text.Pandoc.Shared
 import Text.Pandoc.Writers.MediaWiki (highlightingLangs)
 import Text.Pandoc.Writers.Shared (toLegacyTable)
 
-data WriterState = WriterState {
+newtype WriterState = WriterState {
   listLevel :: Text -- String at the beginning of items
 }
 

src/Text/Pandoc/XML.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE LambdaCase        #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ViewPatterns      #-}
 {- |
@@ -54,7 +55,7 @@ escapeStringForXML = T.concatMap escapeCharForXML . T.filter isLegalXMLChar
 
 -- | Escape newline characters as 

 escapeNls :: Text -> Text
-escapeNls = T.concatMap $ \x -> case x of
+escapeNls = T.concatMap $ \case
   '\n' -> "
"
   c    -> T.singleton c
 

test/Tests/Helpers.hs

@@ -1,7 +1,6 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE FlexibleInstances    #-}
-{-# LANGUAGE TypeSynonymInstances #-}
 {- |
    Module      : Tests.Helpers
    Copyright   : © 2006-2020 John MacFarlane
@@ -104,7 +103,7 @@ findPandoc = do
              -- cabalv1
              "test-pandoc" : "build" : ps
                -> joinPath (reverse ps) </> "build" </> "pandoc"
-             _ -> error $ "findPandoc: could not find pandoc executable"
+             _ -> error "findPandoc: could not find pandoc executable"
   let pandocPath = pandocDir </> "pandoc"
 #ifdef _WINDOWS
                              <.> "exe"

test/Tests/Old.hs

@@ -14,7 +14,6 @@ module Tests.Old (tests) where
 
 import Prelude
 import Data.Algorithm.Diff
-import Prelude hiding (readFile)
 import Data.List (intercalate)
 import Data.Maybe (catMaybes)
 import System.Exit
@@ -291,7 +290,7 @@ fb2WriterTest pandocPath title opts inputfile normfile =
   where
     formatXML xml = splitTags $ zip xml (drop 1 xml)
     splitTags []               = []
-    splitTags [end]            = fst end : snd end : []
+    splitTags [end]            = [fst end, snd end]
     splitTags (('>','<'):rest) = ">\n" ++ splitTags rest
     splitTags ((c,_):rest)     = c : splitTags rest
     ignoreBinary = unlines . filter (not . startsWith "<binary ") . lines

test/Tests/Readers/Docx.hs

@@ -33,7 +33,7 @@ import Text.Pandoc.UTF8 as UTF8
 -- tests. Since we do our own normalization, we want to make sure
 -- we're doing it right.
 
-data NoNormPandoc = NoNormPandoc {unNoNorm :: Pandoc}
+newtype NoNormPandoc = NoNormPandoc {unNoNorm :: Pandoc}
                  deriving Show
 
 noNorm :: Pandoc -> NoNormPandoc

test/Tests/Readers/Man.hs

@@ -68,7 +68,7 @@ tests = [
   testGroup "Escapes" [
       "fonts" =:
       "aa\\fIbb\\fRcc"
-      =?>para (str "aa" <> (emph $ str "bb") <> str "cc")
+      =?>para (str "aa" <> emph (str "bb") <> str "cc")
     , "nested fonts" =:
       "\\f[BI]hi\\f[I] there\\f[R]"
       =?> para (emph (strong (text "hi") <> text " there"))

test/Tests/Readers/Muse.hs

@@ -51,7 +51,7 @@ simpleTable' n capt headers rows
           (TableFoot nullAttr [])
   where
     toRow = Row nullAttr . map simpleCell
-    toHeaderRow l = if null l then [] else [toRow l]
+    toHeaderRow l = [toRow l | not (null l)]
 
 -- Tables don't round-trip yet
 --

test/Tests/Readers/Org/Block/Table.hs

@@ -35,7 +35,7 @@ simpleTable'' capt spec headers rows
           (TableFoot nullAttr [])
   where
     toRow = Row nullAttr . map simpleCell
-    toHeaderRow l = if null l then [] else [toRow l]
+    toHeaderRow l = [toRow l | not (null l)]
 
 tests :: [TestTree]
 tests =

test/Tests/Readers/Org/Directive.hs

@@ -30,7 +30,7 @@ testWithFiles :: (ToString c)
               -> (T.Text, c)    -- ^ (input, expected value)
               -> TestTree
 testWithFiles fileDefs = test (orgWithFiles fileDefs)
-  where
+
 orgWithFiles :: [(FilePath, BS.ByteString)] -> T.Text -> Pandoc
 orgWithFiles fileDefs input =
   let readOrg' = readOrg def{ readerExtensions = getDefaultExtensions "org" }

test/Tests/Readers/Txt2Tags.hs

@@ -54,7 +54,7 @@ simpleTable'' spec headers rows
           (TableFoot nullAttr [])
   where
     toRow = Row nullAttr . map simpleCell
-    toHeaderRow l = if null l then [] else [toRow l]
+    toHeaderRow l = [toRow l | not (null l)]
 
 tests :: [TestTree]
 tests =

test/Tests/Shared.hs

@@ -35,24 +35,24 @@ tests = [ testGroup "compactifyDL"
 
 testCollapse :: [TestTree]
 testCollapse = map (testCase "collapse")
- [  collapseFilePath (joinPath [ ""]) @?= (joinPath [ ""])
- ,  collapseFilePath (joinPath [ ".","foo"]) @?= (joinPath [ "foo"])
- ,  collapseFilePath (joinPath [ ".",".","..","foo"]) @?= (joinPath [ joinPath ["..", "foo"]])
- ,  collapseFilePath (joinPath [ "..","foo"]) @?= (joinPath [ "..","foo"])
- ,  collapseFilePath (joinPath [ "","bar","..","baz"]) @?= (joinPath [ "","baz"])
- ,  collapseFilePath (joinPath [ "","..","baz"]) @?= (joinPath [ "","..","baz"])
- ,  collapseFilePath (joinPath [ ".","foo","..",".","bar","..",".",".","baz"]) @?= (joinPath [ "baz"])
- ,  collapseFilePath (joinPath [ ".",""]) @?= (joinPath [ ""])
- ,  collapseFilePath (joinPath [ ".",".",""]) @?= (joinPath [ ""])
- ,  collapseFilePath (joinPath [ "..",""]) @?= (joinPath [ ".."])
- ,  collapseFilePath (joinPath [ "..",".",""]) @?= (joinPath [ ".."])
- ,  collapseFilePath (joinPath [ ".","..",""]) @?= (joinPath [ ".."])
- ,  collapseFilePath (joinPath [ "..","..",""]) @?= (joinPath [ "..",".."])
- ,  collapseFilePath (joinPath [ "parent","foo","baz","..","bar"]) @?= (joinPath [ "parent","foo","bar"])
- ,  collapseFilePath (joinPath [ "parent","foo","baz","..","..","bar"]) @?= (joinPath [ "parent","bar"])
- ,  collapseFilePath (joinPath [ "parent","foo",".."]) @?= (joinPath [ "parent"])
- ,  collapseFilePath (joinPath [ "","parent","foo","..","..","bar"]) @?= (joinPath [ "","bar"])
- ,  collapseFilePath (joinPath [ "",".","parent","foo"]) @?= (joinPath [ "","parent","foo"])]
+ [  collapseFilePath (joinPath [ ""]) @?= joinPath [ ""]
+ ,  collapseFilePath (joinPath [ ".","foo"]) @?= joinPath [ "foo"]
+ ,  collapseFilePath (joinPath [ ".",".","..","foo"]) @?= joinPath [ joinPath ["..", "foo"]]
+ ,  collapseFilePath (joinPath [ "..","foo"]) @?= joinPath [ "..","foo"]
+ ,  collapseFilePath (joinPath [ "","bar","..","baz"]) @?= joinPath [ "","baz"]
+ ,  collapseFilePath (joinPath [ "","..","baz"]) @?= joinPath [ "","..","baz"]
+ ,  collapseFilePath (joinPath [ ".","foo","..",".","bar","..",".",".","baz"]) @?= joinPath [ "baz"]
+ ,  collapseFilePath (joinPath [ ".",""]) @?= joinPath [ ""]
+ ,  collapseFilePath (joinPath [ ".",".",""]) @?= joinPath [ ""]
+ ,  collapseFilePath (joinPath [ "..",""]) @?= joinPath [ ".."]
+ ,  collapseFilePath (joinPath [ "..",".",""]) @?= joinPath [ ".."]
+ ,  collapseFilePath (joinPath [ ".","..",""]) @?= joinPath [ ".."]
+ ,  collapseFilePath (joinPath [ "..","..",""]) @?= joinPath [ "..",".."]
+ ,  collapseFilePath (joinPath [ "parent","foo","baz","..","bar"]) @?= joinPath [ "parent","foo","bar"]
+ ,  collapseFilePath (joinPath [ "parent","foo","baz","..","..","bar"]) @?= joinPath [ "parent","bar"]
+ ,  collapseFilePath (joinPath [ "parent","foo",".."]) @?= joinPath [ "parent"]
+ ,  collapseFilePath (joinPath [ "","parent","foo","..","..","bar"]) @?= joinPath [ "","bar"]
+ ,  collapseFilePath (joinPath [ "",".","parent","foo"]) @?= joinPath [ "","parent","foo"]]
 
 testLegacyTable :: [TestTree]
 testLegacyTable =

test/Tests/Writers/OOXML.hs

@@ -48,7 +48,7 @@ displayDiff elemA elemB =
   showDiff (1,1) $ getDiff (lines $ ppContent elemA) (lines $ ppContent elemB)
 
 goldenArchive :: FilePath -> IO Archive
-goldenArchive fp = (toArchive . BL.fromStrict) <$> BS.readFile fp
+goldenArchive fp = toArchive . BL.fromStrict <$> BS.readFile fp
 
 testArchive :: (WriterOptions -> Pandoc -> PandocIO BL.ByteString)
             -> WriterOptions