Add a writer for Markua 0.10 (#7729)

Markua is a markdown variant used by Leanpub.
More information about Markua can be found at https://leanpub.com/markua/read.

Adds a new exported function `writeMarkua` from T.P.Writers.Markdown.
[API change]

Closes #1871.

Co-authored by Tim Wisotzki and Samuel Lemmenmeier.

15 files changed, 1043 insertions, 70 deletions

diff --git a/MANUAL.txt b/MANUAL.txt
index fe551bbce..2e6d53ca6 100644
--- a/MANUAL.txt
+++ b/MANUAL.txt
@@ -316,6 +316,7 @@ header when requesting a document from a URL:
     - `markdown_mmd` ([MultiMarkdown])
     - `markdown_phpextra` ([PHP Markdown Extra])
     - `markdown_strict` (original unextended [Markdown])
+    - `markua` ([Markua])
     - `mediawiki` ([MediaWiki markup])
     - `ms` ([roff ms])
     - `muse` ([Muse]),
@@ -502,6 +503,7 @@ header when requesting a document from a URL:
 [CSL JSON]: https://citeproc-js.readthedocs.io/en/latest/csl-json/markup.html
 [BibTeX]: https://ctan.org/pkg/bibtex
 [BibLaTeX]: https://ctan.org/pkg/biblatex
+[Markua]: https://leanpub.com/markua/read
 
 ## Reader options {.options}
 
diff --git a/data/templates/default.markua b/data/templates/default.markua
new file mode 100644
index 000000000..9f6ca96de
--- /dev/null
+++ b/data/templates/default.markua
@@ -0,0 +1,21 @@
+$if(titleblock)$
+$titleblock$
+
+$endif$
+$for(header-includes)$
+$header-includes$
+
+$endfor$
+$for(include-before)$
+$include-before$
+
+$endfor$
+$if(toc)$
+$table-of-contents$
+
+$endif$
+$body$
+$for(include-after)$
+
+$include-after$
+$endfor$
diff --git a/pandoc.cabal b/pandoc.cabal
index b09b19144..3cad5bce7 100644
--- a/pandoc.cabal
+++ b/pandoc.cabal
@@ -90,6 +90,7 @@ data-files:
                  data/templates/default.epub3
                  data/templates/article.jats_publishing
                  data/templates/affiliations.jats
+                 data/templates/default.markua
                  -- translations
                  data/translations/*.yaml
                  -- source files for reference.docx
@@ -825,6 +826,7 @@ test-suite test-pandoc
                   Tests.Writers.Docx
                   Tests.Writers.RST
                   Tests.Writers.TEI
+                  Tests.Writers.Markua
                   Tests.Writers.Muse
                   Tests.Writers.FB2
                   Tests.Writers.Powerpoint
diff --git a/src/Text/Pandoc/App/FormatHeuristics.hs b/src/Text/Pandoc/App/FormatHeuristics.hs
index a2acfc6d6..e5fe7ad81 100644
--- a/src/Text/Pandoc/App/FormatHeuristics.hs
+++ b/src/Text/Pandoc/App/FormatHeuristics.hs
@@ -54,6 +54,7 @@ formatFromFilePath x =
     ".lhs"      -> Just "markdown+lhs"
     ".ltx"      -> Just "latex"
     ".markdown" -> Just "markdown"
+    ".markua"   -> Just "markua"
     ".mkdn"     -> Just "markdown"
     ".mkd"      -> Just "markdown"
     ".mdwn"     -> Just "markdown"
diff --git a/src/Text/Pandoc/Extensions.hs b/src/Text/Pandoc/Extensions.hs
index ce6a95458..33f615740 100644
--- a/src/Text/Pandoc/Extensions.hs
+++ b/src/Text/Pandoc/Extensions.hs
@@ -432,6 +432,8 @@ getDefaultExtensions "jats_archiving"  = getDefaultExtensions "jats"
 getDefaultExtensions "jats_publishing" = getDefaultExtensions "jats"
 getDefaultExtensions "jats_articleauthoring" = getDefaultExtensions "jats"
 getDefaultExtensions "opml"            = pandocExtensions -- affects notes
+getDefaultExtensions "markua"          = extensionsFromList
+                                          []
 getDefaultExtensions _                 = extensionsFromList
                                           [Ext_auto_identifiers]
 
diff --git a/src/Text/Pandoc/Shared.hs b/src/Text/Pandoc/Shared.hs
index eb0b4acbf..50abe6937 100644
--- a/src/Text/Pandoc/Shared.hs
+++ b/src/Text/Pandoc/Shared.hs
@@ -25,6 +25,7 @@ module Text.Pandoc.Shared (
                      ordNub,
                      findM,
                      -- * Text processing
+                     inquotes,
                      tshow,
                      elemText,
                      notElemText,
@@ -186,6 +187,10 @@ findM p = foldr go (pure Nothing)
 -- Text processing
 --
 
+-- | Wrap double quotes around a Text
+inquotes :: T.Text -> T.Text
+inquotes txt = T.cons '\"' (T.snoc txt '\"')
+
 tshow :: Show a => a -> T.Text
 tshow = T.pack . show
 
diff --git a/src/Text/Pandoc/Writers.hs b/src/Text/Pandoc/Writers.hs
index c348477c2..960b9074c 100644
--- a/src/Text/Pandoc/Writers.hs
+++ b/src/Text/Pandoc/Writers.hs
@@ -51,6 +51,7 @@ module Text.Pandoc.Writers
     , writeLaTeX
     , writeMan
     , writeMarkdown
+    , writeMarkua
     , writeMediaWiki
     , writeMs
     , writeMuse
@@ -190,6 +191,7 @@ writers = [
   ,("csljson"      , TextWriter writeCslJson)
   ,("bibtex"       , TextWriter writeBibTeX)
   ,("biblatex"     , TextWriter writeBibLaTeX)
+  ,("markua"       , TextWriter writeMarkua)
   ]
 
 -- | Retrieve writer, extensions based on formatSpec (format+extensions).
diff --git a/src/Text/Pandoc/Writers/Markdown.hs b/src/Text/Pandoc/Writers/Markdown.hs
index 022dbc24f..bb68d9fee 100644
--- a/src/Text/Pandoc/Writers/Markdown.hs
+++ b/src/Text/Pandoc/Writers/Markdown.hs
@@ -18,6 +18,7 @@ Markdown:  <https://daringfireball.net/projects/markdown/>
 module Text.Pandoc.Writers.Markdown (
   writeMarkdown,
   writeCommonMark,
+  writeMarkua,
   writePlain) where
 import Control.Monad.Reader
 import Control.Monad.State.Strict
@@ -42,7 +43,10 @@ import Text.Pandoc.Templates (renderTemplate)
 import Text.DocTemplates (Val(..), Context(..), FromContext(..))
 import Text.Pandoc.Walk
 import Text.Pandoc.Writers.HTML (writeHtml5String)
-import Text.Pandoc.Writers.Markdown.Inline (inlineListToMarkdown, linkAttributes, attrsToMarkdown)
+import Text.Pandoc.Writers.Markdown.Inline (inlineListToMarkdown, 
+                                            linkAttributes, 
+                                            attrsToMarkdown, 
+                                            attrsToMarkua)
 import Text.Pandoc.Writers.Markdown.Types (MarkdownVariant(..),
                                            WriterState(..),
                                            WriterEnv(..),
@@ -77,6 +81,26 @@ writeCommonMark opts document =
                    enableExtension Ext_intraword_underscores $
                      writerExtensions opts }
 
+-- | Convert Pandoc to Markua.
+writeMarkua :: PandocMonad m => WriterOptions -> Pandoc -> m Text
+writeMarkua opts document =
+  evalMD (pandocToMarkdown opts' document) def{ envVariant = Markua } def
+ where
+  opts' = opts{   writerExtensions =
+                  enableExtension Ext_hard_line_breaks $
+                  enableExtension Ext_pipe_tables $
+                  -- required for fancy list enumerators
+                  enableExtension Ext_fancy_lists $
+                  enableExtension Ext_startnum $
+                  enableExtension Ext_strikeout $
+                  enableExtension Ext_subscript $
+                  enableExtension Ext_superscript $
+                  enableExtension Ext_definition_lists $
+                  enableExtension Ext_smart $
+                  enableExtension Ext_footnotes
+                    mempty }
+
+
 pandocTitleBlock :: Doc Text -> [Doc Text] -> Doc Text -> Doc Text
 pandocTitleBlock tit auths dat =
   hang 2 (text "% ") tit <> cr <>
@@ -327,8 +351,15 @@ blockToMarkdown' opts (Div attrs ils) = do
   contents <- blockListToMarkdown opts ils
   variant <- asks envVariant
   return $
-    case () of
-         _ | isEnabled Ext_fenced_divs opts &&
+     case () of
+         _ | variant == Markua -> 
+                   case () of
+                        () | "blurb" `elem` classes' -> prefixed "B> " contents <> blankline
+                           | "aside" `elem` classes' -> prefixed "A> " contents <> blankline
+                           -- | necessary to enable option to create a bibliography
+                           | (take 3 (T.unpack id')) == "ref" -> contents <> blankline
+                           | otherwise -> contents <> blankline
+           | isEnabled Ext_fenced_divs opts &&
              attrs /= nullAttr ->
                 let attrsToMd = if variant == Commonmark
                                 then attrsToMarkdown
@@ -408,6 +439,7 @@ blockToMarkdown' opts b@(RawBlock f str) = do
       | f `elem` ["markdown", "markdown_github", "markdown_phpextra",
                   "markdown_mmd", "markdown_strict"]
          -> return $ literal str <> literal "\n"
+    Markua -> renderEmpty
     _ | isEnabled Ext_raw_attribute opts -> rawAttribBlock
       | f `elem` ["html", "html5", "html4"]
       , isEnabled Ext_markdown_attribute opts
@@ -419,17 +451,19 @@ blockToMarkdown' opts b@(RawBlock f str) = do
       , isEnabled Ext_raw_tex opts
          -> return $ literal str <> literal "\n"
     _ -> renderEmpty
-blockToMarkdown' opts HorizontalRule =
-  return $ blankline <> literal (T.replicate (writerColumns opts) "-") <> blankline
+blockToMarkdown' opts HorizontalRule = do
+  variant <- asks envVariant
+  let indicator = case variant of
+                        Markua -> "* * *"
+                        _ -> T.replicate (writerColumns opts) "-"
+  return $ blankline <> literal indicator <> blankline
 blockToMarkdown' opts (Header level attr inlines) = do
-
   -- first, if we're putting references at the end of a section, we
   -- put them here.
   blkLevel <- asks envBlockLevel
   refs <- if writerReferenceLocation opts == EndOfSection && blkLevel == 1
           then notesAndRefs opts
           else return empty
-
   variant <- asks envVariant
   -- we calculate the id that would be used by auto_identifiers
   -- so we know whether to print an explicit identifier
@@ -442,7 +476,8 @@ blockToMarkdown' opts (Header level attr inlines) = do
                                  && id' == autoId -> empty
                    (id',_,_)   | isEnabled Ext_mmd_header_identifiers opts ->
                                     space <> brackets (literal id')
-                   _ | isEnabled Ext_header_attributes opts ||
+                   _ | variant == Markua -> attrsToMarkua attr
+                     | isEnabled Ext_header_attributes opts ||
                        isEnabled Ext_attributes opts ->
                                     space <> attrsToMarkdown attr
                      | otherwise -> empty
@@ -476,6 +511,8 @@ blockToMarkdown' opts (Header level attr inlines) = do
             -- ghc interprets '#' characters in column 1 as linenum specifiers.
             _ | variant == PlainText || isEnabled Ext_literate_haskell opts ->
                 contents <> blankline
+            _ | variant == Markua -> attr' <> cr <> literal (T.replicate level "#") 
+                                        <> space <> contents <> blankline
             _ -> literal (T.replicate level "#") <> space <> contents <> attr' <> blankline
 
   return $ refs <> hdr
@@ -492,9 +529,11 @@ blockToMarkdown' opts (CodeBlock attribs str) = do
           backticks <> attrs <> cr <> literal str <> cr <> backticks <> blankline
            | isEnabled Ext_fenced_code_blocks opts ->
           tildes <> attrs <> cr <> literal str <> cr <> tildes <> blankline
-     _ -> nest (writerTabStop opts) (literal str) <> blankline
+     _ | variant == Markua -> blankline <> attrsToMarkua attribs <> cr <> backticks <> cr <> 
+                                literal str <> cr <> backticks <> cr <> blankline
+       | otherwise -> nest (writerTabStop opts) (literal str) <> blankline
    where
-     endlineLen c = maybe 3 ((+1) . maximum) $ nonEmpty $
+     endlineLen c = maybe 3 ((+1) . maximum) $ nonEmpty
                         [T.length ln
                          | ln <- map trim (T.lines str)
                          , T.pack [c,c,c] `T.isPrefixOf` ln
@@ -581,24 +620,29 @@ blockToMarkdown' opts t@(Table _ blkCapt specs thead tbody tfoot) = do
   return $ nst (tbl $$ caption'') $$ blankline
 blockToMarkdown' opts (BulletList items) = do
   contents <- inList $ mapM (bulletListItemToMarkdown opts) items
-  return $ (if isTightList items then vcat else vsep) contents <> blankline
+  return $ (if isTightList items then vcat else vsep) 
+                  contents <> blankline
 blockToMarkdown' opts (OrderedList (start,sty,delim) items) = do
   variant <- asks envVariant
   let start' = if variant == Commonmark || isEnabled Ext_startnum opts
                   then start
                   else 1
   let sty'   = if isEnabled Ext_fancy_lists opts then sty else DefaultStyle
-  let delim' = if isEnabled Ext_fancy_lists opts
-                  then delim
-                  else if variant == Commonmark &&
-                           (delim == OneParen || delim == TwoParens)
-                       then OneParen -- commonmark only supports one paren
-                       else DefaultDelim
+  let delim' | isEnabled Ext_fancy_lists opts =
+               case variant of 
+                   -- Markua supports 'fancy' enumerators, but no TwoParens
+                   Markua -> if delim == TwoParens then OneParen else delim
+                   _ -> delim
+             | variant == Commonmark && --commonmark only supports one paren
+                   (delim == OneParen || delim == TwoParens) = OneParen
+             | otherwise = DefaultDelim
   let attribs = (start', sty', delim')
   let markers  = orderedListMarkers attribs
-  let markers' = map (\m -> if T.length m < 3
-                               then m <> T.replicate (3 - T.length m) " "
-                               else m) markers
+  let markers' = case variant of
+                        Markua -> markers
+                        _ -> map (\m -> if T.length m < 3
+                                   then m <> T.replicate (3 - T.length m) " "
+                                   else m) markers
   contents <- inList $
               zipWithM (orderedListItemToMarkdown opts) markers' items
   return $ (if isTightList items then vcat else vsep) contents <> blankline
@@ -712,10 +756,13 @@ itemEndsWithTightList bs =
 -- | Convert bullet list item (list of blocks) to markdown.
 bulletListItemToMarkdown :: PandocMonad m => WriterOptions -> [Block] -> MD m (Doc Text)
 bulletListItemToMarkdown opts bs = do
+  variant <- asks envVariant
   let exts = writerExtensions opts
   contents <- blockListToMarkdown opts $ taskListItemToAscii exts bs
   let sps = T.replicate (writerTabStop opts - 2) " "
-  let start = literal $ "- " <> sps
+  let start = case variant of
+              Markua -> literal "* "
+              _      -> literal $ "- " <> sps
   -- remove trailing blank line if item ends with a tight list
   let contents' = if itemEndsWithTightList bs
                      then chomp contents <> cr
@@ -725,19 +772,22 @@ bulletListItemToMarkdown opts bs = do
 -- | Convert ordered list item (a list of blocks) to markdown.
 orderedListItemToMarkdown :: PandocMonad m
                           => WriterOptions -- ^ options
-                          -> Text        -- ^ list item marker
+                          -> Text          -- ^ list item marker
                           -> [Block]       -- ^ list item (list of blocks)
                           -> MD m (Doc Text)
 orderedListItemToMarkdown opts marker bs = do
   let exts = writerExtensions opts
   contents <- blockListToMarkdown opts $ taskListItemToAscii exts bs
+  variant <- asks envVariant
   let sps = case writerTabStop opts - T.length marker of
                    n | n > 0 -> literal $ T.replicate n " "
                    _ -> literal " "
   let ind = if isEnabled Ext_four_space_rule opts
                then writerTabStop opts
                else max (writerTabStop opts) (T.length marker + 1)
-  let start = literal marker <> sps
+  let start = case variant of
+              Markua -> literal marker <> " "
+              _      -> literal marker <> sps
   -- remove trailing blank line if item ends with a tight list
   let contents' = if itemEndsWithTightList bs
                      then chomp contents <> cr
@@ -756,7 +806,10 @@ definitionListItemToMarkdown opts (label, defs) = do
      then do
        let tabStop = writerTabStop opts
        variant <- asks envVariant
-       let leader  = if variant == PlainText then "   " else ":  "
+       let leader  = case variant of
+                        PlainText -> "   "
+                        Markua -> ":"
+                        _ -> ":  "
        let sps = case writerTabStop opts - 3 of
                       n | n > 0   -> literal $ T.replicate n " "
                       _ -> literal " "
@@ -827,6 +880,7 @@ blockListToMarkdown opts blocks = do
       isListBlock _                  = False
       commentSep
         | variant == PlainText        = Null
+        | variant == Markua           = Null
         | 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/Markdown/Inline.hs b/src/Text/Pandoc/Writers/Markdown/Inline.hs
index d299d31b2..0bf70e80e 100644
--- a/src/Text/Pandoc/Writers/Markdown/Inline.hs
+++ b/src/Text/Pandoc/Writers/Markdown/Inline.hs
@@ -13,7 +13,8 @@
 module Text.Pandoc.Writers.Markdown.Inline (
   inlineListToMarkdown,
   linkAttributes,
-  attrsToMarkdown
+  attrsToMarkdown,
+  attrsToMarkua
   ) where
 import Control.Monad.Reader
 import Control.Monad.State.Strict
@@ -95,6 +96,11 @@ escapeText opts = T.pack . go' . T.unpack
                   , isAlphaNum x -> c : '_' : x : go xs
                 _                -> c : go cs
 
+-- Escape the escape character, as well as formatting pairs
+escapeMarkuaString :: Text -> Text
+escapeMarkuaString s = foldr (uncurry T.replace) s [("--","~-~-"),
+                        ("**","~*~*"),("//","~/~/"),("^^","~^~^"),(",,","~,~,")]
+ 
 attrsToMarkdown :: Attr -> Doc Text
 attrsToMarkdown attribs = braces $ hsep [attribId, attribClasses, attribKeys]
         where attribId = case attribs of
@@ -116,9 +122,56 @@ attrsToMarkdown attribs = braces $ hsep [attribId, attribClasses, attribKeys]
               escAttrChar '\\' = literal "\\\\"
               escAttrChar c    = literal $ T.singleton c
 
+attrsToMarkua:: Attr -> Doc Text
+attrsToMarkua attributes
+     | null list = empty
+     | otherwise = braces $ intercalateDocText list
+        where attrId = case attributes of
+                        ("",_,_) -> []
+                        (i,_,_)  -> [literal $ "id: " <> i]
+              -- all non explicit (key,value) attributes besides id are getting
+              -- a default class key to be Markua conform
+              attrClasses = case attributes of
+                             (_,[],_) -> []
+                             (_,classes,_) -> map (escAttr . ("class: " <>))
+                                classes
+              attrKeyValues = case attributes of
+                               (_,_,[]) -> []
+                               (_,_,keyvalues) -> map ((\(k,v) -> escAttr k
+                                              <> ": " <> escAttr v) . 
+                                              preprocessKeyValues) keyvalues
+              escAttr          = mconcat . map escAttrChar . T.unpack
+              escAttrChar '"'  = literal "\""
+              escAttrChar c    = literal $ T.singleton c
+
+              list = concat [attrId, attrClasses, attrKeyValues]
+
+              -- if attribute key is alt, caption, title then content
+              -- gets wrapped inside quotes
+              -- attribute gets removed
+              preprocessKeyValues :: (Text, Text) -> (Text, Text)
+              preprocessKeyValues (key,value)
+                 | key == "alt" ||
+                   key == "caption" ||
+                   key == "title" = (key, inquotes value)
+                 | otherwise = (key,value)
+              intercalateDocText :: [Doc Text] -> Doc Text
+              intercalateDocText [] = empty
+              intercalateDocText [x] = x
+              intercalateDocText (x:xs) = x <> ", " <> (intercalateDocText xs)
+
+-- | Add a (key, value) pair to Pandoc attr type
+addKeyValueToAttr :: Attr -> (Text,Text) -> Attr
+addKeyValueToAttr (ident,classes,kvs) (key,value) 
+    | not (T.null key) && not (T.null value) = (ident,
+                                                classes,
+                                                (key,value): kvs)
+    | otherwise = (ident,classes,kvs)
+
 linkAttributes :: WriterOptions -> Attr -> Doc Text
 linkAttributes opts attr =
-  if (isEnabled Ext_link_attributes opts || isEnabled Ext_attributes opts) && attr /= nullAttr
+  if (isEnabled Ext_link_attributes opts || 
+        isEnabled Ext_attributes opts) && attr /= nullAttr
      then attrsToMarkdown attr
      else empty
 
@@ -283,6 +336,7 @@ inlineToMarkdown opts (Span attrs ils) = do
              _ -> id
          $ case variant of
                 PlainText -> contents
+                Markua -> "`" <> contents <> "`" <> attrsToMarkua attrs
                 _     | attrs == nullAttr -> contents
                       | isEnabled Ext_bracketed_spans opts ->
                         let attrs' = if attrs /= nullAttr
@@ -396,60 +450,75 @@ inlineToMarkdown opts (Quoted DoubleQuote lst) = do
                    then "&ldquo;" <> contents <> "&rdquo;"
                    else "“" <> contents <> "”"
 inlineToMarkdown opts (Code attr str) = do
+  variant <- asks envVariant
   let tickGroups   = filter (T.any (== '`')) $ T.group str
   let longest      = maybe 0 maximum $ nonEmpty $ map T.length tickGroups
   let marker       = T.replicate (longest + 1) "`"
   let spacer       = if longest == 0 then "" else " "
   let attrsEnabled = isEnabled Ext_inline_code_attributes opts ||
                      isEnabled Ext_attributes opts
-  let attrs        = if attrsEnabled && attr /= nullAttr
-                        then attrsToMarkdown attr
-                        else empty
-  variant <- asks envVariant
+  let attrs = case variant of
+                       Markua -> attrsToMarkua attr
+                       _   -> if attrsEnabled && attr /= nullAttr
+                                        then attrsToMarkdown attr
+                                        else empty
   case variant of
      PlainText -> return $ literal str
      _     ->  return $ literal
                   (marker <> spacer <> str <> spacer <> marker) <> attrs
 inlineToMarkdown opts (Str str) = do
   variant <- asks envVariant
-  let str' = (if writerPreferAscii opts
-                 then toHtml5Entities
-                 else id) .
-             (if isEnabled Ext_smart opts
-                 then unsmartify opts
-                 else id) .
-             (if variant == PlainText
-                 then id
-                 else escapeText opts) $ str
+  let str' = case variant of
+                Markua -> escapeMarkuaString str
+                _ -> (if writerPreferAscii opts
+                        then toHtml5Entities
+                        else id) .
+                     (if isEnabled Ext_smart opts
+                        then unsmartify opts
+                        else id) .
+                     (if variant == PlainText
+                        then id
+                        else escapeText opts) $ str
   return $ literal str'
-inlineToMarkdown opts (Math InlineMath str) =
-  case writerHTMLMathMethod opts of
-       WebTeX url -> inlineToMarkdown opts
-                       (Image nullAttr [Str str] (url <> urlEncode str, str))
-       _ | isEnabled Ext_tex_math_dollars opts ->
-             return $ "$" <> literal str <> "$"
-         | isEnabled Ext_tex_math_single_backslash opts ->
-             return $ "\\(" <> literal str <> "\\)"
-         | isEnabled Ext_tex_math_double_backslash opts ->
-             return $ "\\\\(" <> literal str <> "\\\\)"
-         | otherwise -> do
-             variant <- asks envVariant
-             texMathToInlines InlineMath str >>=
-               inlineListToMarkdown opts .
-                 (if variant == PlainText then makeMathPlainer else id)
-inlineToMarkdown opts (Math DisplayMath str) =
-  case writerHTMLMathMethod opts of
-      WebTeX url -> (\x -> blankline <> x <> blankline) `fmap`
-             inlineToMarkdown opts (Image nullAttr [Str str]
-                    (url <> urlEncode str, str))
-      _ | isEnabled Ext_tex_math_dollars opts ->
-            return $ "$$" <> literal str <> "$$"
-        | isEnabled Ext_tex_math_single_backslash opts ->
-            return $ "\\[" <> literal str <> "\\]"
-        | isEnabled Ext_tex_math_double_backslash opts ->
-            return $ "\\\\[" <> literal str <> "\\\\]"
-        | otherwise -> (\x -> cr <> x <> cr) `fmap`
-            (texMathToInlines DisplayMath str >>= inlineListToMarkdown opts)
+inlineToMarkdown opts (Math InlineMath str) = do
+  variant <- asks envVariant
+  case () of
+    _ | variant == Markua -> return $ "`" <> literal str <> "`" <> "$"
+      | otherwise -> case writerHTMLMathMethod opts of
+          WebTeX url -> inlineToMarkdown opts
+                          (Image nullAttr [Str str] (url <> urlEncode str, str))
+          _ | isEnabled Ext_tex_math_dollars opts ->
+                return $ "$" <> literal str <> "$"
+            | isEnabled Ext_tex_math_single_backslash opts ->
+                return $ "\\(" <> literal str <> "\\)"
+            | isEnabled Ext_tex_math_double_backslash opts ->
+                return $ "\\\\(" <> literal str <> "\\\\)"
+            | otherwise -> 
+                texMathToInlines InlineMath str >>=
+                  inlineListToMarkdown opts .
+                    (if variant == PlainText then makeMathPlainer else id)
+     
+inlineToMarkdown opts (Math DisplayMath str) = do
+  variant <- asks envVariant
+  case () of
+    _ | variant == Markua -> do
+        let attributes = attrsToMarkua (addKeyValueToAttr ("",[],[]) 
+                                                        ("format", "latex"))
+        return $ blankline <> attributes <> cr <> literal "```" <> cr 
+            <> literal str <> cr <> literal "```" <> blankline
+      | otherwise -> case writerHTMLMathMethod opts of
+          WebTeX url -> (\x -> blankline <> x <> blankline) `fmap`
+                 inlineToMarkdown opts (Image nullAttr [Str str]
+                        (url <> urlEncode str, str))
+          _ | isEnabled Ext_tex_math_dollars opts ->
+                return $ "$$" <> literal str <> "$$"
+            | isEnabled Ext_tex_math_single_backslash opts ->
+                return $ "\\[" <> literal str <> "\\]"
+            | isEnabled Ext_tex_math_double_backslash opts ->
+                return $ "\\\\[" <> literal str <> "\\\\]"
+            | otherwise -> (\x -> cr <> x <> cr) `fmap`
+                (texMathToInlines DisplayMath str >>= inlineListToMarkdown opts)
+
 inlineToMarkdown opts il@(RawInline f str) = do
   let tickGroups = filter (T.any (== '`')) $ T.group str
   let numticks   = 1 + maybe 0 maximum (nonEmpty (map T.length tickGroups))
@@ -469,6 +538,7 @@ inlineToMarkdown opts il@(RawInline f str) = do
       | f `elem` ["markdown", "markdown_github", "markdown_phpextra",
                   "markdown_mmd", "markdown_strict"]
          -> return $ literal str
+    Markua -> renderEmpty
     _ | isEnabled Ext_raw_attribute opts -> rawAttribInline
       | f `elem` ["html", "html5", "html4"]
       , isEnabled Ext_raw_html opts
@@ -563,6 +633,11 @@ inlineToMarkdown opts lnk@(Link attr@(ident,classes,kvs) txt (src, tit)) = do
     PlainText
       | useAuto -> return $ literal srcSuffix
       | otherwise -> return linktext
+    Markua
+      | T.null tit -> return $ result <> attrsToMarkua attr
+      | otherwise ->  return $ result <> attrsToMarkua attributes
+        where result = "[" <> linktext <> "](" <> (literal src) <> ")"
+              attributes = addKeyValueToAttr attr ("title", tit)
     _ | useAuto -> return $ "<" <> literal srcSuffix <> ">"
       | useRefLinks ->
            let first  = "[" <> linktext <> "]"
@@ -594,9 +669,16 @@ inlineToMarkdown opts img@(Image attr alternate (source, tit))
                then [Str ""]
                else alternate
   linkPart <- inlineToMarkdown opts (Link attr txt (source, tit))
+  alt <- inlineListToMarkdown opts alternate
+  let attributes | variant == Markua = attrsToMarkua $ 
+            addKeyValueToAttr (addKeyValueToAttr attr ("title", tit)) 
+            ("alt", render (Just (writerColumns opts)) alt) 
+                 | otherwise = empty
   return $ case variant of
-             PlainText -> "[" <> linkPart <> "]"
-             _     -> "!" <> linkPart
+                PlainText -> "[" <> linkPart <> "]"
+                Markua -> cr <> attributes <> cr <> literal "![](" <> 
+                            literal source <> ")" <> cr
+                _ -> "!" <> linkPart
 inlineToMarkdown opts (Note contents) = do
   modify (\st -> st{ stNotes = contents : stNotes st })
   st <- get
diff --git a/src/Text/Pandoc/Writers/Markdown/Types.hs b/src/Text/Pandoc/Writers/Markdown/Types.hs
index a1d0d14e4..060446811 100644
--- a/src/Text/Pandoc/Writers/Markdown/Types.hs
+++ b/src/Text/Pandoc/Writers/Markdown/Types.hs
@@ -45,7 +45,8 @@ data WriterEnv = WriterEnv { envInList          :: Bool
                            }
 
 data MarkdownVariant =
-      PlainText
+      Markua
+    | PlainText
     | Commonmark
     | Markdown
     deriving (Show, Eq)
diff --git a/test/Tests/Old.hs b/test/Tests/Old.hs
index e03d94e85..450449946 100644
--- a/test/Tests/Old.hs
+++ b/test/Tests/Old.hs
@@ -228,6 +228,7 @@ tests pandocPath =
     , test' "reader" ["-f", "ipynb", "-t", "html"]
       "ipynb/rank.ipynb" "ipynb/rank.out.html"
     ]
+  , testGroup "markua" [ testGroup "writer" $ writerTests' "markua"]
   ]
  where
     test'           = test pandocPath
diff --git a/test/Tests/Writers/Markua.hs b/test/Tests/Writers/Markua.hs
new file mode 100644
index 000000000..62239f3da
--- /dev/null
+++ b/test/Tests/Writers/Markua.hs
@@ -0,0 +1,40 @@
+{-# LANGUAGE OverloadedStrings #-}
+module Tests.Writers.Markua (tests) where
+
+import Test.Tasty
+import Tests.Helpers
+import Text.Pandoc
+import Text.Pandoc.Arbitrary ()
+import Text.Pandoc.Builder
+
+{-
+  "my test" =: X =?> Y
+
+is shorthand for
+
+  test html "my test" $ X =?> Y
+
+which is in turn shorthand for
+
+  test html "my test" (X,Y)
+-}
+
+infix 4 =:
+(=:) :: (ToString a, ToPandoc a)
+     => String -> (a, String) -> TestTree
+(=:) = test (purely (writeMarkua def) . toPandoc)
+
+tests :: [TestTree]
+tests = [ testGroup "simple blurb/aside"
+          ["blurb"          =: divWith ("",["blurb"],[]) (bulletList [para "blurb content"])
+                           =?> "B> * blurb content"
+          ,"aside"          =: divWith ("",["aside"],[]) (bulletList [para "aside list"])
+                           =?> "A> * aside list"
+          ]
+         ,testGroup "multiclass blurb/aside"
+          ["blurb"          =: divWith ("",["blurb", "otherclass"],[]) (bulletList [para "blurb content"])
+                           =?> "B> * blurb content"
+          ,"aside"          =: divWith ("",["otherclass", "aside"],[]) (bulletList [para "aside list"])
+                           =?> "A> * aside list"
+          ]
+         ]
diff --git a/test/tables.markua b/test/tables.markua
new file mode 100644
index 000000000..b82264fd7
--- /dev/null
+++ b/test/tables.markua
@@ -0,0 +1,58 @@
+Simple table with caption:
+
+| Right | Left | Center | Default |
+|------:|:-----|:------:|---------|
+|    12 | 12   |   12   | 12      |
+|   123 | 123  |  123   | 123     |
+|     1 | 1    |   1    | 1       |
+
+Demonstration of simple table syntax.
+
+Simple table without caption:
+
+| Right | Left | Center | Default |
+|------:|:-----|:------:|---------|
+|    12 | 12   |   12   | 12      |
+|   123 | 123  |  123   | 123     |
+|     1 | 1    |   1    | 1       |
+
+Simple table indented two spaces:
+
+| Right | Left | Center | Default |
+|------:|:-----|:------:|---------|
+|    12 | 12   |   12   | 12      |
+|   123 | 123  |  123   | 123     |
+|     1 | 1    |   1    | 1       |
+
+Demonstration of simple table syntax.
+
+Multiline table with caption:
+
+| Centered Header | Left Aligned | Right Aligned | Default aligned                                       |
+|:---------------:|:-------------|--------------:|:------------------------------------------------------|
+|      First      | row          |          12.0 | Example of a row that spans multiple lines.           |
+|     Second      | row          |           5.0 | Here’s another one. Note the blank line between rows. |
+
+Here’s the caption. It may span multiple lines.
+
+Multiline table without caption:
+
+| Centered Header | Left Aligned | Right Aligned | Default aligned                                       |
+|:---------------:|:-------------|--------------:|:------------------------------------------------------|
+|      First      | row          |          12.0 | Example of a row that spans multiple lines.           |
+|     Second      | row          |           5.0 | Here’s another one. Note the blank line between rows. |
+
+Table without column headers:
+
+|     |     |     |     |
+|----:|:----|:---:|----:|
+|  12 | 12  | 12  |  12 |
+| 123 | 123 | 123 | 123 |
+|   1 | 1   |  1  |   1 |
+
+Multiline table without column headers:
+
+|        |     |      |                                                       |
+|:------:|:----|-----:|-------------------------------------------------------|
+| First  | row | 12.0 | Example of a row that spans multiple lines.           |
+| Second | row |  5.0 | Here’s another one. Note the blank line between rows. |
diff --git a/test/test-pandoc.hs b/test/test-pandoc.hs
index 476762aac..fcb157fb7 100644
--- a/test/test-pandoc.hs
+++ b/test/test-pandoc.hs
@@ -50,6 +50,7 @@ import qualified Tests.Writers.Powerpoint
 import qualified Tests.Writers.RST
 import qualified Tests.Writers.AnnotatedTable
 import qualified Tests.Writers.TEI
+import qualified Tests.Writers.Markua
 import Text.Pandoc.Shared (inDirectory)
 
 tests :: FilePath -> TestTree
@@ -72,6 +73,7 @@ tests pandocPath = testGroup "pandoc tests"
           , testGroup "Docx" Tests.Writers.Docx.tests
           , testGroup "RST" Tests.Writers.RST.tests
           , testGroup "TEI" Tests.Writers.TEI.tests
+          , testGroup "markua" Tests.Writers.Markua.tests
           , testGroup "Muse" Tests.Writers.Muse.tests
           , testGroup "FB2" Tests.Writers.FB2.tests
           , testGroup "PowerPoint" Tests.Writers.Powerpoint.tests
diff --git a/test/writer.markua b/test/writer.markua
new file mode 100644
index 000000000..1c5b44cc2
--- /dev/null
+++ b/test/writer.markua
@@ -0,0 +1,700 @@
+This is a set of tests for pandoc. Most of them are adapted from John Gruber’s
+markdown test suite.
+
+* * *
+
+{id: headers}
+# Headers
+
+{id: level-2-with-an-embedded-link}
+## Level 2 with an [embedded link](/url)
+
+{id: level-3-with-emphasis}
+### Level 3 with *emphasis*
+
+{id: level-4}
+#### Level 4
+
+{id: level-5}
+##### Level 5
+
+{id: level-1}
+# Level 1
+
+{id: level-2-with-emphasis}
+## Level 2 with *emphasis*
+
+{id: level-3}
+### Level 3
+
+with no blank line
+
+{id: level-2}
+## Level 2
+
+with no blank line
+
+* * *
+
+{id: paragraphs}
+# Paragraphs
+
+Here’s a regular paragraph.
+
+In Markdown 1.0.0 and earlier. Version 8. This line turns into a list item.
+Because a hard-wrapped line in the middle of a paragraph looked like a list
+item.
+
+Here’s one with a bullet. * criminey.
+
+There should be a hard line break
+here.
+
+* * *
+
+{id: block-quotes}
+# Block Quotes
+
+E-mail style:
+
+> This is a block quote. It is pretty short.
+
+> Code in a block quote:
+>
+> ```
+> sub status {
+>     print "working";
+> }
+> ```
+>
+> A list:
+>
+> 1. item one
+> 2. item two
+>
+> Nested block quotes:
+>
+> > nested
+>
+> > nested
+
+This should not be a block quote: 2 > 1.
+
+And a following paragraph.
+
+* * *
+
+{id: code-blocks}
+# Code Blocks
+
+Code:
+
+```
+---- (should be four hyphens)
+
+sub status {
+    print "working";
+}
+
+this code block is indented by one tab
+```
+
+And:
+
+```
+    this code block is indented by two tabs
+
+These should not be escaped:  \$ \\ \> \[ \{
+```
+
+* * *
+
+{id: lists}
+# Lists
+
+{id: unordered}
+## Unordered
+
+Asterisks tight:
+
+* asterisk 1
+* asterisk 2
+* asterisk 3
+
+Asterisks loose:
+
+* asterisk 1
+
+* asterisk 2
+
+* asterisk 3
+
+Pluses tight:
+
+* Plus 1
+* Plus 2
+* Plus 3
+
+Pluses loose:
+
+* Plus 1
+
+* Plus 2
+
+* Plus 3
+
+Minuses tight:
+
+* Minus 1
+* Minus 2
+* Minus 3
+
+Minuses loose:
+
+* Minus 1
+
+* Minus 2
+
+* Minus 3
+
+{id: ordered}
+## Ordered
+
+Tight:
+
+1. First
+2. Second
+3. Third
+
+and:
+
+1. One
+2. Two
+3. Three
+
+Loose using tabs:
+
+1. First
+
+2. Second
+
+3. Third
+
+and using spaces:
+
+1. One
+
+2. Two
+
+3. Three
+
+Multiple paragraphs:
+
+1. Item 1, graf one.
+
+    Item 1. graf two. The quick brown fox jumped over the lazy dog’s back.
+
+2. Item 2.
+
+3. Item 3.
+
+{id: nested}
+## Nested
+
+* Tab
+    * Tab
+        * Tab
+
+Here’s another:
+
+1. First
+2. Second:
+    * Fee
+    * Fie
+    * Foe
+3. Third
+
+Same thing but with paragraphs:
+
+1. First
+
+2. Second:
+
+    * Fee
+    * Fie
+    * Foe
+
+3. Third
+
+{id: tabs-and-spaces}
+## Tabs and spaces
+
+* this is a list item indented with tabs
+
+* this is a list item indented with spaces
+
+    * this is an example list item indented with tabs
+
+    * this is an example list item indented with spaces
+
+{id: fancy-list-markers}
+## Fancy list markers
+
+2) begins with 2
+
+3) and now 3
+
+    with a continuation
+
+    iv. sublist with roman numerals, starting with 4
+    v. more items
+        A) a subsublist
+        B) a subsublist
+
+Nesting:
+
+A. Upper Alpha
+    I. Upper Roman.
+        6) Decimal start with 6
+            c) Lower alpha with paren
+
+Autonumbering:
+
+1. Autonumber.
+2. More.
+    1. Nested.
+
+Should not be a list item:
+
+M.A. 2007
+
+B. Williams
+
+* * *
+
+{id: definition-lists}
+# Definition Lists
+
+Tight using spaces:
+
+apple
+: red fruit
+
+orange
+: orange fruit
+
+banana
+: yellow fruit
+
+Tight using tabs:
+
+apple
+: red fruit
+
+orange
+: orange fruit
+
+banana
+: yellow fruit
+
+Loose:
+
+apple
+
+: red fruit
+
+orange
+
+: orange fruit
+
+banana
+
+: yellow fruit
+
+Multiple blocks with italics:
+
+*apple*
+
+: red fruit
+
+    contains seeds, crisp, pleasant to taste
+
+*orange*
+
+: orange fruit
+
+    ```
+    { orange code block }
+    ```
+
+    > orange block quote
+
+Multiple definitions, tight:
+
+apple
+: red fruit
+: computer
+
+orange
+: orange fruit
+: bank
+
+Multiple definitions, loose:
+
+apple
+
+: red fruit
+
+: computer
+
+orange
+
+: orange fruit
+
+: bank
+
+Blank line after term, indented marker, alternate markers:
+
+apple
+
+: red fruit
+
+: computer
+
+orange
+
+: orange fruit
+
+    1. sublist
+    2. sublist
+
+{id: html-blocks}
+# HTML Blocks
+
+Simple block on one line:
+
+foo
+
+And nested without indentation:
+
+foo
+
+bar
+
+Interpreted markdown in a table:
+
+This is *emphasized*
+And this is **strong**
+Here’s a simple block:
+
+foo
+
+This should be a code block, though:
+
+```
+<div>
+    foo
+</div>
+```
+
+As should this:
+
+```
+<div>foo</div>
+```
+
+Now, nested:
+
+foo
+
+This should just be an HTML comment:
+
+Multiline:
+
+Code block:
+
+```
+<!-- Comment -->
+```
+
+Just plain comment, with trailing spaces on the line:
+
+Code:
+
+```
+<hr />
+```
+
+Hr’s:
+
+* * *
+
+{id: inline-markup}
+# Inline Markup
+
+This is *emphasized*, and so *is this*.
+
+This is **strong**, and so **is this**.
+
+An *[emphasized link](/url)*.
+
+***This is strong and em.***
+
+So is ***this*** word.
+
+***This is strong and em.***
+
+So is ***this*** word.
+
+This is code: `>`, `$`, `\`, `\$`, `<html>`.
+
+~~This is *strikeout*.~~
+
+Superscripts: a^bc^d a^*hello*^ a^hello there^.
+
+Subscripts: H~2~O, H~23~O, H~many of them~O.
+
+These should not be superscripts or subscripts, because of the unescaped spaces:
+a^b c^d, a~b c~d.
+
+* * *
+
+{id: smart-quotes-ellipses-dashes}
+# Smart quotes, ellipses, dashes
+
+"Hello," said the spider. "'Shelob' is my name."
+
+'A', 'B', and 'C' are letters.
+
+'Oak,' 'elm,' and 'beech' are names of trees. So is 'pine.'
+
+'He said, "I want to go."' Were you alive in the 70’s?
+
+Here is some quoted '`code`' and a "[quoted
+link](http://example.com/?foo=1&bar=2)".
+
+Some dashes: one—two — three—four — five.
+
+Dashes between numbers: 5–7, 255–66, 1987–1999.
+
+Ellipses…and…and….
+
+* * *
+
+{id: latex}
+# LaTeX
+
+* 
+* `2+2=4`$
+* `x \in y`$
+* `\alpha \wedge \omega`$
+* `223`$
+* `p`$-Tree
+* Here’s some display math:
+
+    {format: latex}
+    ```
+    \frac{d}{dx}f(x)=\lim_{h\to 0}\frac{f(x+h)-f(x)}{h}
+    ```
+* Here’s one that has a line break in it: `\alpha + \omega \times x^2`$.
+
+These shouldn’t be math:
+
+* To get the famous equation, write `$e = mc^2$`.
+* $22,000 is a *lot* of money. So is $34,000. (It worked if "lot" is
+    emphasized.)
+* Shoes ($20) and socks ($5).
+* Escaped `$`: $73 *this should be emphasized* 23$.
+
+Here’s a LaTeX table:
+
+* * *
+
+{id: special-characters}
+# Special Characters
+
+Here is some unicode:
+
+* I hat: Î
+* o umlaut: ö
+* section: §
+* set membership: ∈
+* copyright: ©
+
+AT&T has an ampersand in their name.
+
+AT&T is another way to write it.
+
+This & that.
+
+4 < 5.
+
+6 > 5.
+
+Backslash: \
+
+Backtick: `
+
+Asterisk: *
+
+Underscore: _
+
+Left brace: {
+
+Right brace: }
+
+Left bracket: [
+
+Right bracket: ]
+
+Left paren: (
+
+Right paren: )
+
+Greater-than: >
+
+Hash: #
+
+Period: .
+
+Bang: !
+
+Plus: +
+
+Minus: -
+
+* * *
+
+{id: links}
+# Links
+
+{id: explicit}
+## Explicit
+
+Just a [URL](/url/).
+
+[URL and title](/url/){title: "title"}.
+
+[URL and title](/url/){title: "title preceded by two spaces"}.
+
+[URL and title](/url/){title: "title preceded by a tab"}.
+
+[URL and title](/url/){title: "title with "quotes" in it"}
+
+[URL and title](/url/){title: "title with single quotes"}
+
+[with_underscore](/url/with_underscore)
+
+[Email link](mailto:nobody@nowhere.net)
+
+[Empty]().
+
+{id: reference}
+## Reference
+
+Foo [bar](/url/).
+
+With [embedded [brackets]](/url/).
+
+[b](/url/) by itself should be a link.
+
+Indented [once](/url).
+
+Indented [twice](/url).
+
+Indented [thrice](/url).
+
+This should [not][] be a link.
+
+```
+[not]: /url
+```
+
+Foo [bar](/url/){title: "Title with "quotes" inside"}.
+
+Foo [biz](/url/){title: "Title with "quote" inside"}.
+
+{id: with-ampersands}
+## With ampersands
+
+Here’s a [link with an ampersand in the URL](http://example.com/?foo=1&bar=2).
+
+Here’s a link with an amersand in the link text:
+[AT&T](http://att.com/){title: "AT&T"}.
+
+Here’s an [inline link](/script?foo=1&bar=2).
+
+Here’s an [inline link in pointy braces](/script?foo=1&bar=2).
+
+{id: autolinks}
+## Autolinks
+
+With an ampersand:
+[http:~/~/example.com/?foo=1&bar=2](http://example.com/?foo=1&bar=2){class: uri}
+
+* In a list?
+* [http:~/~/example.com/](http://example.com/){class: uri}
+* It should.
+
+An e-mail address: [nobody@nowhere.net](mailto:nobody@nowhere.net){class: email}
+
+> Blockquoted: [http:~/~/example.com/](http://example.com/){class: uri}
+
+Auto-links should not occur here: `<http://example.com/>`
+
+```
+or here: <http://example.com/>
+```
+
+* * *
+
+{id: images}
+# Images
+
+From "Voyage dans la Lune" by Georges Melies (1902):
+
+{alt: "lalune", title: "Voyage dans la Lune"}
+![](lalune.jpg)
+
+Here is a movie
+{alt: "movie"}
+![](movie.jpg)
+icon.
+
+* * *
+
+{id: footnotes}
+# Footnotes
+
+Here is a footnote reference,[^1] and another.[^2] This should *not* be a
+footnote reference, because it contains a space.[^my note] Here is an inline
+note.[^3]
+
+> Notes can go in quotes.[^4]
+
+1. And in list items.[^5]
+
+This paragraph should not be part of the note, as it is not indented.
+
+[^1]: Here is the footnote. It can go anywhere after the footnote reference. It
+    need not be placed at the end of the document.
+
+[^2]: Here’s the long note. This one contains multiple blocks.
+
+    Subsequent blocks are indented to show that they belong to the footnote (as
+    with list items).
+
+    ```
+      { <code> }
+    ```
+
+    If you want, you can indent every line, but you can also be lazy and just
+    indent the first line of each block.
+
+[^3]: This is *easier* to type. Inline notes may contain
+    [links](http://google.com) and `]` verbatim characters, as well as
+    [bracketed text].
+
+[^4]: In quote.
+
+[^5]: In list.