Added a LineBlock block element.

See second point in jgm/pandoc#1852 and discussion in jgm/pandoc#1545.

Substantial changes in pandoc are still needed.

Text/Pandoc/Builder.hs

@@ -147,6 +147,7 @@ module Text.Pandoc.Builder ( module Text.Pandoc.Definition
                            -- * Block list builders
                            , para
                            , plain
+                           , lineBlock
                            , codeBlockWith
                            , codeBlock
                            , rawBlock
@@ -430,6 +431,9 @@ plain ils = if isNull ils
                then mempty
                else singleton . Plain . toList $ ils
 
+lineBlock :: [Inlines] -> Blocks
+lineBlock = singleton . LineBlock . map toList
+
 -- | A code block with attributes.
 codeBlockWith :: Attr -> String -> Blocks
 codeBlockWith attrs = singleton . CodeBlock attrs

Text/Pandoc/Definition.hs

@@ -211,6 +211,7 @@ instance Ord Format where
 data Block
     = Plain [Inline]        -- ^ Plain text, not a paragraph
     | Para [Inline]         -- ^ Paragraph
+    | LineBlock [[Inline]]  -- ^ Multiple non-breaking lines
     | CodeBlock Attr String -- ^ Code block (literal) with attributes
     | RawBlock Format String -- ^ Raw block
     | BlockQuote [Block]    -- ^ Block quote (list of blocks)

Text/Pandoc/Walk.hs

@@ -186,6 +186,7 @@ instance Walkable Inline Inline where
 instance Walkable Inline Block where
   walk f (Para xs)                = Para $ walk f xs
   walk f (Plain xs)               = Plain $ walk f xs
+  walk f (LineBlock xs)           = LineBlock $ walk f xs
   walk f (CodeBlock attr s)       = CodeBlock attr s
   walk f (RawBlock t s)           = RawBlock t s
   walk f (BlockQuote bs)          = BlockQuote $ walk f bs
@@ -200,6 +201,7 @@ instance Walkable Inline Block where
 
   walkM f (Para xs)                = Para <$> walkM f xs
   walkM f (Plain xs)               = Plain <$> walkM f xs
+  walkM f (LineBlock xs)           = LineBlock <$> walkM f xs
   walkM f (CodeBlock attr s)       = return $ CodeBlock attr s
   walkM f (RawBlock t s)           = return $ RawBlock t s
   walkM f (BlockQuote bs)          = BlockQuote <$> walkM f bs
@@ -218,6 +220,7 @@ instance Walkable Inline Block where
 
   query f (Para xs)                = query f xs
   query f (Plain xs)               = query f xs
+  query f (LineBlock xs)           = query f xs
   query f (CodeBlock attr s)       = mempty
   query f (RawBlock t s)           = mempty
   query f (BlockQuote bs)          = query f bs
@@ -233,6 +236,7 @@ instance Walkable Inline Block where
 instance Walkable Block Block where
   walk f (Para xs)                = f $ Para $ walk f xs
   walk f (Plain xs)               = f $ Plain $ walk f xs
+  walk f (LineBlock xs)           = f $ LineBlock $ walk f xs
   walk f (CodeBlock attr s)       = f $ CodeBlock attr s
   walk f (RawBlock t s)           = f $ RawBlock t s
   walk f (BlockQuote bs)          = f $ BlockQuote $ walk f bs
@@ -248,6 +252,7 @@ instance Walkable Block Block where
 
   walkM f (Para xs)                = Para <$> walkM f xs >>= f
   walkM f (Plain xs)               = Plain <$> walkM f xs >>= f
+  walkM f (LineBlock xs)           = LineBlock <$> walkM f xs >>= f
   walkM f (CodeBlock attr s)       = f $ CodeBlock attr s
   walkM f (RawBlock t s)           = f $ RawBlock t s
   walkM f (BlockQuote bs)          = BlockQuote <$> walkM f bs >>= f
@@ -265,6 +270,7 @@ instance Walkable Block Block where
 
   query f (Para xs)                = f (Para xs) <> query f xs
   query f (Plain xs)               = f (Plain xs) <> query f xs
+  query f (LineBlock xs)           = f (LineBlock xs) <> query f xs
   query f (CodeBlock attr s)       = f $ CodeBlock attr s
   query f (RawBlock t s)           = f $ RawBlock t s
   query f (BlockQuote bs)          = f (BlockQuote bs) <> query f bs