From 74ad1a04ad410785bed62c47367f3981217e19e7 Mon Sep 17 00:00:00 2001
From: Michael Howell <michael@notriddle.com>
Date: Tue, 6 May 2025 12:30:32 -0700
Subject: [PATCH] Make definition lists handle blank lines more like normal
 lists

---
 .../Commonmark/Extensions/DefinitionList.hs   |  9 ++++--
 .../test/definition_lists.md                  | 31 +++++++++++++++++++
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/commonmark-extensions/src/Commonmark/Extensions/DefinitionList.hs b/commonmark-extensions/src/Commonmark/Extensions/DefinitionList.hs
index 33b3902..e324452 100644
--- a/commonmark-extensions/src/Commonmark/Extensions/DefinitionList.hs
+++ b/commonmark-extensions/src/Commonmark/Extensions/DefinitionList.hs
@@ -160,10 +160,13 @@ definitionListDefinitionBlockSpec = BlockSpec
      , blockCanContain     = const True
      , blockContainsLines  = False
      , blockParagraph      = False
-     , blockContinue       = \node@(Node ndata _cs) -> do
-         pos <- getPosition
+     , blockContinue       = \node@(Node ndata children) -> do
          let definitionIndent = fromDyn (blockData ndata) 0
-         gobbleSpaces definitionIndent <|> 0 <$ lookAhead blankLine
+         -- a marker followed by two blanks is just an empty item:
+         pos <- getPosition
+         case blockBlanks ndata of
+              _:_ | null children -> lookAhead blankLine
+              _ -> () <$ gobbleSpaces definitionIndent <|> lookAhead blankLine
          return $! (pos, node)
      , blockConstructor    = fmap mconcat . renderChildren
      , blockFinalize       = defaultFinalizer
diff --git a/commonmark-extensions/test/definition_lists.md b/commonmark-extensions/test/definition_lists.md
index 2c91e6e..1144854 100644
--- a/commonmark-extensions/test/definition_lists.md
+++ b/commonmark-extensions/test/definition_lists.md
@@ -301,3 +301,34 @@ bim
 </dd>
 </dl>
 ````````````````````````````````
+
+<https://github.com/jgm/commonmark-hs/issues/165
+
+```````````````````````````````` example
+HTML In a Definition List
+:
+  <div>
+    <span>One space</span>
+  </div>
+
+
+HTML *Outside* a Definition List
+:
+
+  <div>
+    <span>Two Spaces</span>
+  </div>
+.
+<dl>
+<dt>HTML In a Definition List</dt>
+<dd> <div>
+   <span>One space</span>
+ </div>
+</dd>
+<dt>HTML <em>Outside</em> a Definition List</dt>
+<dd></dd>
+</dl>
+  <div>
+    <span>Two Spaces</span>
+  </div>
+````````````````````````````````