Remove block constructor Null from the code base.

It has been removed from pandoc-types.

29 files changed, 3 insertions, 38 deletions

diff --git a/src/Text/Pandoc/Shared.hs b/src/Text/Pandoc/Shared.hs
index bbd0f3d18..115e59907 100644
--- a/src/Text/Pandoc/Shared.hs
+++ b/src/Text/Pandoc/Shared.hs
@@ -547,7 +547,6 @@ makeSections numbering mbBaseLevel bs =
     xs' <- go xs
     rest' <- go rest
     return $ Div attr xs' : rest'
-  go (Null:xs) = go xs
   go (x:xs) = (x :) <$> go xs
   go [] = return []
 
@@ -848,7 +847,6 @@ blockToInlines (Table _ _ _ (TableHead _ hbd) bodies (TableFoot _ fbd)) =
     unTableBody (TableBody _ _ hd bd) = hd <> bd
     unTableBodies = concatMap unTableBody
 blockToInlines (Div _ blks) = blocksToInlines' blks
-blockToInlines Null = mempty
 blockToInlines (Figure _ _ body) = blocksToInlines' body
 
 blocksToInlinesWithSep :: Inlines -> [Block] -> Inlines
diff --git a/src/Text/Pandoc/Slides.hs b/src/Text/Pandoc/Slides.hs
index 73c426a6c..3e83c82ff 100644
--- a/src/Text/Pandoc/Slides.hs
+++ b/src/Text/Pandoc/Slides.hs
@@ -30,7 +30,7 @@ getSlideLevel = go 6
 
 -- | Prepare a block list to be passed to makeSections.
 prepSlides :: Int -> [Block] -> [Block]
-prepSlides slideLevel = ensureStartWithH . splitHrule . extractRefsHeader . filter (/= Null)
+prepSlides slideLevel = ensureStartWithH . splitHrule . extractRefsHeader
   where splitHrule (HorizontalRule : Header n attr xs : ys)
                        | n == slideLevel = Header slideLevel attr xs : splitHrule ys
         splitHrule (HorizontalRule : xs) = Header slideLevel nullAttr [Str "\0"] :
diff --git a/src/Text/Pandoc/Writers/AsciiDoc.hs b/src/Text/Pandoc/Writers/AsciiDoc.hs
index 29b6ff971..2a9401a4f 100644
--- a/src/Text/Pandoc/Writers/AsciiDoc.hs
+++ b/src/Text/Pandoc/Writers/AsciiDoc.hs
@@ -145,7 +145,6 @@ blockToAsciiDoc :: PandocMonad m
                 => WriterOptions -- ^ Options
                 -> Block         -- ^ Block element
                 -> ADW m (Doc Text)
-blockToAsciiDoc _ Null = return empty
 blockToAsciiDoc opts (Div (id',"section":_,_)
                        (Header level (_,cls,kvs) ils : xs)) = do
   hdr <- blockToAsciiDoc opts (Header level (id',cls,kvs) ils)
diff --git a/src/Text/Pandoc/Writers/ConTeXt.hs b/src/Text/Pandoc/Writers/ConTeXt.hs
index b5543b036..b375b6c2b 100644
--- a/src/Text/Pandoc/Writers/ConTeXt.hs
+++ b/src/Text/Pandoc/Writers/ConTeXt.hs
@@ -179,7 +179,6 @@ toLabel z = T.concatMap go z
 
 -- | Convert Pandoc block element to ConTeXt.
 blockToConTeXt :: PandocMonad m => Block -> WM m (Doc Text)
-blockToConTeXt Null = return empty
 blockToConTeXt (Div attr@(_,"section":_,_)
                  (Header level _ title' : xs)) = do
   header' <- sectionHeader attr level title' SectionHeading
diff --git a/src/Text/Pandoc/Writers/DocBook.hs b/src/Text/Pandoc/Writers/DocBook.hs
index 3f6d3cfda..90bee50e1 100644
--- a/src/Text/Pandoc/Writers/DocBook.hs
+++ b/src/Text/Pandoc/Writers/DocBook.hs
@@ -167,7 +167,6 @@ imageToDocBook _ attr src = selfClosingTag "imagedata" $
 
 -- | Convert a Pandoc block element to DocBook.
 blockToDocBook :: PandocMonad m => WriterOptions -> Block -> DB m (Doc Text)
-blockToDocBook _ Null = return empty
 -- Add ids to paragraphs in divs with ids - this is needed for
 -- pandoc-citeproc to get link anchors in bibliographies:
 blockToDocBook opts (Div (id',"section":_,_) (Header lvl (_,classes,attrs) ils : xs)) = do
diff --git a/src/Text/Pandoc/Writers/Docx.hs b/src/Text/Pandoc/Writers/Docx.hs
index 8970d75b8..e3956c5ef 100644
--- a/src/Text/Pandoc/Writers/Docx.hs
+++ b/src/Text/Pandoc/Writers/Docx.hs
@@ -835,7 +835,6 @@ blockToOpenXML :: (PandocMonad m) => WriterOptions -> Block -> WS m [Content]
 blockToOpenXML opts blk = withDirection $ blockToOpenXML' opts blk
 
 blockToOpenXML' :: (PandocMonad m) => WriterOptions -> Block -> WS m [Content]
-blockToOpenXML' _ Null = return []
 blockToOpenXML' opts (Div (ident,_classes,kvs) bs) = do
   stylemod <- case lookup dynamicStyleKey kvs of
                    Just (fromString . T.unpack -> sty) -> do
diff --git a/src/Text/Pandoc/Writers/DokuWiki.hs b/src/Text/Pandoc/Writers/DokuWiki.hs
index e2b2a988c..e2d948125 100644
--- a/src/Text/Pandoc/Writers/DokuWiki.hs
+++ b/src/Text/Pandoc/Writers/DokuWiki.hs
@@ -100,8 +100,6 @@ blockToDokuWiki :: PandocMonad m
                 -> Block         -- ^ Block element
                 -> DokuWiki m Text
 
-blockToDokuWiki _ Null = return ""
-
 blockToDokuWiki opts (Div _attrs bs) = do
   contents <- blockListToDokuWiki opts bs
   return $ contents <> "\n"
diff --git a/src/Text/Pandoc/Writers/FB2.hs b/src/Text/Pandoc/Writers/FB2.hs
index e2d9deffe..7e62f2a5a 100644
--- a/src/Text/Pandoc/Writers/FB2.hs
+++ b/src/Text/Pandoc/Writers/FB2.hs
@@ -361,7 +361,6 @@ blockToXml (Table _ blkCapt specs thead tbody tfoot) = do
       align_str AlignCenter  = "center"
       align_str AlignRight   = "right"
       align_str AlignDefault = "left"
-blockToXml Null = return []
 blockToXml (Figure _attr (Caption _ longcapt) body) =
   let alt = blocksToInlines longcapt
       addAlt (Image imgattr [] tgt) = Image imgattr alt tgt
diff --git a/src/Text/Pandoc/Writers/HTML.hs b/src/Text/Pandoc/Writers/HTML.hs
index 4a1934387..f99166f22 100644
--- a/src/Text/Pandoc/Writers/HTML.hs
+++ b/src/Text/Pandoc/Writers/HTML.hs
@@ -725,7 +725,6 @@ adjustNumbers opts doc =
    showSecNum = T.intercalate "." . map tshow
 
 blockToHtmlInner :: PandocMonad m => WriterOptions -> Block -> StateT WriterState m Html
-blockToHtmlInner _ Null = return mempty
 blockToHtmlInner opts (Plain lst) = inlineListToHtml opts lst
 blockToHtmlInner opts (Para lst) = do
   slideVariant <- gets stSlideVariant
diff --git a/src/Text/Pandoc/Writers/Haddock.hs b/src/Text/Pandoc/Writers/Haddock.hs
index c2bcddf83..4f79b6c4e 100644
--- a/src/Text/Pandoc/Writers/Haddock.hs
+++ b/src/Text/Pandoc/Writers/Haddock.hs
@@ -93,7 +93,6 @@ blockToHaddock :: PandocMonad m
                => WriterOptions -- ^ Options
                -> Block         -- ^ Block element
                -> StateT WriterState m (Doc Text)
-blockToHaddock _ Null = return empty
 blockToHaddock opts (Div _ ils) = do
   contents <- blockListToHaddock opts ils
   return $ contents <> blankline
diff --git a/src/Text/Pandoc/Writers/ICML.hs b/src/Text/Pandoc/Writers/ICML.hs
index 5f660bc2d..a35699b46 100644
--- a/src/Text/Pandoc/Writers/ICML.hs
+++ b/src/Text/Pandoc/Writers/ICML.hs
@@ -382,7 +382,6 @@ blockToICML opts style (Table attr blkCapt specs thead tbody tfoot) =
 blockToICML opts style (Div (_ident, _, kvs) lst) =
   let dynamicStyle = maybeToList $ lookup dynamicStyleKey kvs
   in  blocksToICML opts (dynamicStyle <> style) lst
-blockToICML _ _ Null = return empty
 blockToICML opts style (Figure attr capt@(Caption _ longcapt) body) =
   case body of
     [Plain [img@(Image {})]] -> do
diff --git a/src/Text/Pandoc/Writers/JATS.hs b/src/Text/Pandoc/Writers/JATS.hs
index f19be1445..6b382367d 100644
--- a/src/Text/Pandoc/Writers/JATS.hs
+++ b/src/Text/Pandoc/Writers/JATS.hs
@@ -252,7 +252,6 @@ fixLineBreak x = x
 
 -- | Convert a Pandoc block element to JATS.
 blockToJATS :: PandocMonad m => WriterOptions -> Block -> JATS m (Doc Text)
-blockToJATS _ Null = return empty
 blockToJATS opts (Div (id',"section":_,kvs) (Header _lvl _ ils : xs)) = do
   let idAttr = [ ("id", writerIdentifierPrefix opts <> escapeNCName id')
                | not (T.null id')]
diff --git a/src/Text/Pandoc/Writers/Jira.hs b/src/Text/Pandoc/Writers/Jira.hs
index 7b637268b..8e20253bf 100644
--- a/src/Text/Pandoc/Writers/Jira.hs
+++ b/src/Text/Pandoc/Writers/Jira.hs
@@ -103,7 +103,6 @@ toJiraBlocks blocks = do
         Para xs              -> singleton . Jira.Para <$> toJiraInlines xs
         Plain xs             -> singleton . Jira.Para <$> toJiraInlines xs
         RawBlock fmt cs      -> rawBlockToJira fmt cs
-        Null                 -> return mempty
         Table _ blkCapt specs thead tbody tfoot -> singleton <$> do
           let (_, _, _, hd, body) = toLegacyTable blkCapt specs thead tbody tfoot
           headerRow <- if all null hd
diff --git a/src/Text/Pandoc/Writers/LaTeX.hs b/src/Text/Pandoc/Writers/LaTeX.hs
index 6dd259dae..1f57565fe 100644
--- a/src/Text/Pandoc/Writers/LaTeX.hs
+++ b/src/Text/Pandoc/Writers/LaTeX.hs
@@ -274,7 +274,6 @@ isListBlock _                  = False
 blockToLaTeX :: PandocMonad m
              => Block     -- ^ Block to convert
              -> LW m (Doc Text)
-blockToLaTeX Null = return empty
 blockToLaTeX (Div attr@(identifier,"block":dclasses,_)
              (Header _ _ ils : bs)) = do
   let blockname
diff --git a/src/Text/Pandoc/Writers/Man.hs b/src/Text/Pandoc/Writers/Man.hs
index 1ea5b8650..66aa8854b 100644
--- a/src/Text/Pandoc/Writers/Man.hs
+++ b/src/Text/Pandoc/Writers/Man.hs
@@ -110,7 +110,6 @@ blockToMan :: PandocMonad m
            => WriterOptions -- ^ Options
            -> Block         -- ^ Block element
            -> StateT WriterState m (Doc Text)
-blockToMan _ Null = return empty
 blockToMan opts (Div _ bs) = blockListToMan opts bs
 blockToMan opts (Plain inlines) =
   splitSentences <$> inlineListToMan opts inlines
diff --git a/src/Text/Pandoc/Writers/Markdown.hs b/src/Text/Pandoc/Writers/Markdown.hs
index 95dedb0b5..6822c6c1a 100644
--- a/src/Text/Pandoc/Writers/Markdown.hs
+++ b/src/Text/Pandoc/Writers/Markdown.hs
@@ -368,7 +368,6 @@ blockToMarkdown' :: PandocMonad m
                  => WriterOptions -- ^ Options
                  -> Block         -- ^ Block element
                  -> MD m (Doc Text)
-blockToMarkdown' _ Null = return empty
 blockToMarkdown' opts (Div attrs ils) = do
   contents <- blockListToMarkdown opts ils
   variant <- asks envVariant
@@ -858,8 +857,8 @@ blockListToMarkdown opts blocks = do
       isListBlock (DefinitionList _) = True
       isListBlock _                  = False
       commentSep
-        | variant == PlainText        = Null
-        | variant == Markua           = Null
+        | variant == PlainText        = Plain []
+        | variant == Markua           = Plain []
         | isEnabled Ext_raw_html opts = RawBlock "html" "<!-- -->\n"
         | otherwise                   = RawBlock "markdown" "&nbsp;\n"
   mconcat <$> mapM (blockToMarkdown opts) (fixBlocks blocks)
diff --git a/src/Text/Pandoc/Writers/MediaWiki.hs b/src/Text/Pandoc/Writers/MediaWiki.hs
index a244a52ff..baf35406c 100644
--- a/src/Text/Pandoc/Writers/MediaWiki.hs
+++ b/src/Text/Pandoc/Writers/MediaWiki.hs
@@ -84,8 +84,6 @@ blockToMediaWiki :: PandocMonad m
                  => Block         -- ^ Block element
                  -> MediaWikiWriter m Text
 
-blockToMediaWiki Null = return ""
-
 blockToMediaWiki (Div attrs bs) = do
   contents <- blockListToMediaWiki bs
   return $ render Nothing (tagWithAttrs "div" attrs) <> "\n\n" <>
diff --git a/src/Text/Pandoc/Writers/Ms.hs b/src/Text/Pandoc/Writers/Ms.hs
index 938ee881e..1635d13c4 100644
--- a/src/Text/Pandoc/Writers/Ms.hs
+++ b/src/Text/Pandoc/Writers/Ms.hs
@@ -129,7 +129,6 @@ blockToMs :: PandocMonad m
           => WriterOptions -- ^ Options
           -> Block         -- ^ Block element
           -> MS m (Doc Text)
-blockToMs _ Null = return empty
 blockToMs opts (Div (ident,cls,kvs) bs) = do
   let anchor = if T.null ident
                   then empty
diff --git a/src/Text/Pandoc/Writers/Muse.hs b/src/Text/Pandoc/Writers/Muse.hs
index c254746b4..80fbf5898 100644
--- a/src/Text/Pandoc/Writers/Muse.hs
+++ b/src/Text/Pandoc/Writers/Muse.hs
@@ -279,7 +279,6 @@ blockToMuse (Table _ blkCapt specs thead tbody tfoot) =
               (length aligns :| length widths : map length (headers:rows))
     isSimple = onlySimpleTableCells (headers : rows) && all (== 0) widths
 blockToMuse (Div _ bs) = flatBlockListToMuse bs
-blockToMuse Null = return empty
 blockToMuse (Figure attr capt body) = do
   blockToMuse (figureDiv attr capt body)
 
diff --git a/src/Text/Pandoc/Writers/OpenDocument.hs b/src/Text/Pandoc/Writers/OpenDocument.hs
index 38a04341f..a96c9cd1a 100644
--- a/src/Text/Pandoc/Writers/OpenDocument.hs
+++ b/src/Text/Pandoc/Writers/OpenDocument.hs
@@ -396,7 +396,6 @@ blockToOpenDocument o = \case
     b@(RawBlock f s) -> if f == Format "opendocument"
                         then return $ text $ T.unpack s
                         else empty <$ report (BlockNotRendered b)
-    Null             -> return empty
     Figure a capt b  -> figure a capt b
     where
       defList       b = do setInDefinitionList True
diff --git a/src/Text/Pandoc/Writers/Org.hs b/src/Text/Pandoc/Writers/Org.hs
index a962705d1..dc7a566bc 100644
--- a/src/Text/Pandoc/Writers/Org.hs
+++ b/src/Text/Pandoc/Writers/Org.hs
@@ -109,7 +109,6 @@ isRawFormat f =
 blockToOrg :: PandocMonad m
            => Block         -- ^ Block element
            -> Org m (Doc Text)
-blockToOrg Null = return empty
 blockToOrg (Div (_, ["cell", "code"], _) (CodeBlock attr t : bs)) = do
   -- ipynb code cell
   let (ident, classes, kvs) = attr
diff --git a/src/Text/Pandoc/Writers/Powerpoint/Presentation.hs b/src/Text/Pandoc/Writers/Powerpoint/Presentation.hs
index 520cf4826..577389740 100644
--- a/src/Text/Pandoc/Writers/Powerpoint/Presentation.hs
+++ b/src/Text/Pandoc/Writers/Powerpoint/Presentation.hs
@@ -1046,7 +1046,6 @@ blockIsBlank
       Figure _ _ bls -> all blockIsBlank bls
       Table{} -> False
       Div _ bls -> all blockIsBlank bls
-      Null -> True
 
 textIsBlank :: T.Text -> Bool
 textIsBlank = T.all isSpace
diff --git a/src/Text/Pandoc/Writers/RST.hs b/src/Text/Pandoc/Writers/RST.hs
index d2ba258fe..a9ee4694d 100644
--- a/src/Text/Pandoc/Writers/RST.hs
+++ b/src/Text/Pandoc/Writers/RST.hs
@@ -241,7 +241,6 @@ bordered contents c =
 blockToRST :: PandocMonad m
            => Block         -- ^ Block element
            -> RST m (Doc Text)
-blockToRST Null = return empty
 blockToRST (Div ("",["title"],[]) _) = return empty
   -- this is generated by the rst reader and can safely be
   -- omitted when we're generating rst
diff --git a/src/Text/Pandoc/Writers/RTF.hs b/src/Text/Pandoc/Writers/RTF.hs
index 2f13627e6..0b1d36eda 100644
--- a/src/Text/Pandoc/Writers/RTF.hs
+++ b/src/Text/Pandoc/Writers/RTF.hs
@@ -230,7 +230,6 @@ blockToRTF :: PandocMonad m
            -> Alignment -- ^ alignment
            -> Block     -- ^ block to convert
            -> m Text
-blockToRTF _ _ Null = return ""
 blockToRTF indent alignment (Div _ bs) =
   blocksToRTF indent alignment bs
 blockToRTF indent alignment (Plain lst) =
diff --git a/src/Text/Pandoc/Writers/TEI.hs b/src/Text/Pandoc/Writers/TEI.hs
index f0efa9952..bb94b35e1 100644
--- a/src/Text/Pandoc/Writers/TEI.hs
+++ b/src/Text/Pandoc/Writers/TEI.hs
@@ -99,7 +99,6 @@ imageToTEI opts attr src = return $ selfClosingTag "graphic" $
 
 -- | Convert a Pandoc block element to TEI.
 blockToTEI :: PandocMonad m => WriterOptions -> Block -> m (Doc Text)
-blockToTEI _ Null = return empty
 blockToTEI opts (Div attr@(_,"section":_,_) (Header lvl _ ils : xs)) =
   do
   -- TEI doesn't allow sections with no content, so insert some if needed
diff --git a/src/Text/Pandoc/Writers/Texinfo.hs b/src/Text/Pandoc/Writers/Texinfo.hs
index ca27a0a32..4436ca1b4 100644
--- a/src/Text/Pandoc/Writers/Texinfo.hs
+++ b/src/Text/Pandoc/Writers/Texinfo.hs
@@ -118,8 +118,6 @@ blockToTexinfo :: PandocMonad m
                => Block     -- ^ Block to convert
                -> TI m (Doc Text)
 
-blockToTexinfo Null = return empty
-
 blockToTexinfo (Div _ bs) = blockListToTexinfo bs
 
 blockToTexinfo (Plain lst) =
diff --git a/src/Text/Pandoc/Writers/Textile.hs b/src/Text/Pandoc/Writers/Textile.hs
index 0f38d91e6..a60eba406 100644
--- a/src/Text/Pandoc/Writers/Textile.hs
+++ b/src/Text/Pandoc/Writers/Textile.hs
@@ -100,8 +100,6 @@ blockToTextile :: PandocMonad m
                -> Block         -- ^ Block element
                -> TW m Text
 
-blockToTextile _ Null = return ""
-
 blockToTextile opts (Div attr bs) = do
   let startTag = render Nothing $ tagWithAttrs "div" attr
   let endTag = "</div>"
diff --git a/src/Text/Pandoc/Writers/XWiki.hs b/src/Text/Pandoc/Writers/XWiki.hs
index 87eda20ac..24e8db8c6 100644
--- a/src/Text/Pandoc/Writers/XWiki.hs
+++ b/src/Text/Pandoc/Writers/XWiki.hs
@@ -87,8 +87,6 @@ blockListToXWiki blocks =
 
 blockToXWiki :: PandocMonad m => Block -> XWikiReader m Text
 
-blockToXWiki Null = return ""
-
 blockToXWiki (Div (id', _, _) blocks) = do
   content <- blockListToXWiki blocks
   return $ genAnchor id' <> content
diff --git a/src/Text/Pandoc/Writers/ZimWiki.hs b/src/Text/Pandoc/Writers/ZimWiki.hs
index 6e8f49ed9..1076732f0 100644
--- a/src/Text/Pandoc/Writers/ZimWiki.hs
+++ b/src/Text/Pandoc/Writers/ZimWiki.hs
@@ -78,8 +78,6 @@ escapeText = T.replace "__" "''__''" .
 -- | Convert Pandoc block element to ZimWiki.
 blockToZimWiki :: PandocMonad m => WriterOptions -> Block -> ZW m Text
 
-blockToZimWiki _ Null = return ""
-
 blockToZimWiki opts (Div _attrs bs) = do
   contents <- blockListToZimWiki opts bs
   return $ contents <> "\n"