Reduce spacing between blocks

Insert empty lines conditionally instead of doing that between every
pair of blocks. It can be improved further, but looks slightly better
than it used to this way.

1 files changed, 29 insertions, 2 deletions

diff --git a/Pancake/Rendering.hs b/Pancake/Rendering.hs
index a917104..55aabd6 100644
--- a/Pancake/Rendering.hs
+++ b/Pancake/Rendering.hs
@@ -484,9 +484,36 @@ renderBlock (P.Div attr b) = do
   i $ renderBlocks b
 renderBlock P.Null = pure ()
 
--- | Renders block elements with empy lines between them.
+-- | Checks whether a block is a list (ordered-, bullet-, or
+-- definition-).
+isList :: P.Block -> Bool
+isList P.OrderedList {} = True
+isList P.BulletList {} = True
+isList P.DefinitionList {} = True
+isList _ = False
+
+-- | Determines whether a line should be skipped before a block.
+skipBefore :: P.Block -> Bool
+skipBefore P.Header {} = True
+skipBefore P.Para {} = True
+skipBefore (P.Div _ (b:_)) = skipBefore b
+skipBefore _ = False
+
+-- | Determines whether a line should be skipped after a block.
+skipAfter :: P.Block -> Bool
+skipAfter P.Header {} = True
+skipAfter P.Para {} = True
+skipAfter (P.Div _ bs@(_:_)) = skipAfter $ last bs
+skipAfter b = isList b
+
+-- | Renders block elements with empty lines between some of them.
 renderBlocks :: [P.Block] -> Renderer ()
-renderBlocks b = sequence_ (intersperse (storeLines [[]]) $ map renderBlock b)
+renderBlocks [] = pure ()
+renderBlocks [b] = renderBlock b
+renderBlocks (b1:bs@(b2:_)) = do
+  renderBlock b1
+  when (skipAfter b1 || skipBefore b2) $ storeLines [[]]
+  renderBlocks bs
 
 -- | Renders a document.
 renderDoc :: Int