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.

26 files changed, 114 insertions, 126 deletions

diff --git a/src/Text/Pandoc/Readers/CSV.hs b/src/Text/Pandoc/Readers/CSV.hs
index 384687a6a..f0edcaa16 100644
--- a/src/Text/Pandoc/Readers/CSV.hs
+++ b/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
diff --git a/src/Text/Pandoc/Readers/CommonMark.hs b/src/Text/Pandoc/Readers/CommonMark.hs
index a85d9aa37..43db6d59a 100644
--- a/src/Text/Pandoc/Readers/CommonMark.hs
+++ b/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
diff --git a/src/Text/Pandoc/Readers/DocBook.hs b/src/Text/Pandoc/Readers/DocBook.hs
index b91e29fa7..084c2788f 100644
--- a/src/Text/Pandoc/Readers/DocBook.hs
+++ b/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
diff --git a/src/Text/Pandoc/Readers/Docx.hs b/src/Text/Pandoc/Readers/Docx.hs
index c9aa2f7c5..9c2f58342 100644
--- a/src/Text/Pandoc/Readers/Docx.hs
+++ b/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.
diff --git a/src/Text/Pandoc/Readers/Docx/Parse.hs b/src/Text/Pandoc/Readers/Docx/Parse.hs
index eab4f4e0d..698d7a88a 100644
--- a/src/Text/Pandoc/Readers/Docx/Parse.hs
+++ b/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 <$> (cmtsElem >>= walkDocument cmts_namespaces)
   in
     case cmts of
diff --git a/src/Text/Pandoc/Readers/DokuWiki.hs b/src/Text/Pandoc/Readers/DokuWiki.hs
index 722701ee2..336be09e5 100644
--- a/src/Text/Pandoc/Readers/DokuWiki.hs
+++ b/src/Text/Pandoc/Readers/DokuWiki.hs
@@ -472,7 +472,7 @@ table = do
                             else ([], rows)
   let attrs = (AlignDefault, ColWidthDefault) <$ 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)
diff --git a/src/Text/Pandoc/Readers/HTML.hs b/src/Text/Pandoc/Readers/HTML.hs
index 3f6e0a1af..761c4cabe 100644
--- a/src/Text/Pandoc/Readers/HTML.hs
+++ b/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)
diff --git a/src/Text/Pandoc/Readers/Haddock.hs b/src/Text/Pandoc/Readers/Haddock.hs
index 8fe5e062c..25d69f040 100644
--- a/src/Text/Pandoc/Readers/Haddock.hs
+++ b/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)
diff --git a/src/Text/Pandoc/Readers/JATS.hs b/src/Text/Pandoc/Readers/JATS.hs
index d3d742de3..69d597212 100644
--- a/src/Text/Pandoc/Readers/JATS.hs
+++ b/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
diff --git a/src/Text/Pandoc/Readers/LaTeX.hs b/src/Text/Pandoc/Readers/LaTeX.hs
index de391e54a..5ceb6e22a 100644
--- a/src/Text/Pandoc/Readers/LaTeX.hs
+++ b/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 [])
 
diff --git a/src/Text/Pandoc/Readers/LaTeX/Lang.hs b/src/Text/Pandoc/Readers/LaTeX/Lang.hs
index 55965c995..814b2fe79 100644
--- a/src/Text/Pandoc/Readers/LaTeX/Lang.hs
+++ b/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
diff --git a/src/Text/Pandoc/Readers/LaTeX/Parsing.hs b/src/Text/Pandoc/Readers/LaTeX/Parsing.hs
index 10e48b45f..c349fe3b1 100644
--- a/src/Text/Pandoc/Readers/LaTeX/Parsing.hs
+++ b/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` ["-","+","@","|",":",","]
diff --git a/src/Text/Pandoc/Readers/LaTeX/SIunitx.hs b/src/Text/Pandoc/Readers/LaTeX/SIunitx.hs
index 49a6d7301..436330d85 100644
--- a/src/Text/Pandoc/Readers/LaTeX/SIunitx.hs
+++ b/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"
diff --git a/src/Text/Pandoc/Readers/Man.hs b/src/Text/Pandoc/Readers/Man.hs
index 12001b534..ed31e1f9a 100644
--- a/src/Text/Pandoc/Readers/Man.hs
+++ b/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
diff --git a/src/Text/Pandoc/Readers/Markdown.hs b/src/Text/Pandoc/Readers/Markdown.hs
index 9b6671f1b..866b074c7 100644
--- a/src/Text/Pandoc/Readers/Markdown.hs
+++ b/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)]
diff --git a/src/Text/Pandoc/Readers/MediaWiki.hs b/src/Text/Pandoc/Readers/MediaWiki.hs
index bcf1228ad..6e7dc3110 100644
--- a/src/Text/Pandoc/Readers/MediaWiki.hs
+++ b/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
 
diff --git a/src/Text/Pandoc/Readers/Muse.hs b/src/Text/Pandoc/Readers/Muse.hs
index 751a37808..b4eea9d3a 100644
--- a/src/Text/Pandoc/Readers/Muse.hs
+++ b/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
diff --git a/src/Text/Pandoc/Readers/Odt/ContentReader.hs b/src/Text/Pandoc/Readers/Odt/ContentReader.hs
index 74120f96a..24391dbf0 100644
--- a/src/Text/Pandoc/Readers/Odt/ContentReader.hs
+++ b/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
diff --git a/src/Text/Pandoc/Readers/Odt/Generic/XMLConverter.hs b/src/Text/Pandoc/Readers/Odt/Generic/XMLConverter.hs
index 5583d64ce..00c636a0d 100644
--- a/src/Text/Pandoc/Readers/Odt/Generic/XMLConverter.hs
+++ b/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
 
diff --git a/src/Text/Pandoc/Readers/Org/Blocks.hs b/src/Text/Pandoc/Readers/Org/Blocks.hs
index c60817d1b..d71cd7faf 100644
--- a/src/Text/Pandoc/Readers/Org/Blocks.hs
+++ b/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)
 
 
diff --git a/src/Text/Pandoc/Readers/Org/ParserState.hs b/src/Text/Pandoc/Readers/Org/ParserState.hs
index 6e2e86373..1e4799e7b 100644
--- a/src/Text/Pandoc/Readers/Org/ParserState.hs
+++ b/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
   }
 
diff --git a/src/Text/Pandoc/Readers/Org/Shared.hs b/src/Text/Pandoc/Readers/Org/Shared.hs
index 3934be6e1..7f72077a4 100644
--- a/src/Text/Pandoc/Readers/Org/Shared.hs
+++ b/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
diff --git a/src/Text/Pandoc/Readers/RST.hs b/src/Text/Pandoc/Readers/RST.hs
index 25682a500..50947c1be 100644
--- a/src/Text/Pandoc/Readers/RST.hs
+++ b/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
diff --git a/src/Text/Pandoc/Readers/TWiki.hs b/src/Text/Pandoc/Readers/TWiki.hs
index ebd87359a..484a6c923 100644
--- a/src/Text/Pandoc/Readers/TWiki.hs
+++ b/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
diff --git a/src/Text/Pandoc/Readers/Textile.hs b/src/Text/Pandoc/Readers/Textile.hs
index b105b587d..6691d8381 100644
--- a/src/Text/Pandoc/Readers/Textile.hs
+++ b/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
                 ]
diff --git a/src/Text/Pandoc/Readers/Txt2Tags.hs b/src/Text/Pandoc/Readers/Txt2Tags.hs
index 245df6f08..5c5b3c4e9 100644
--- a/src/Text/Pandoc/Readers/Txt2Tags.hs
+++ b/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)