Working on parsing single newlines

src/MdToHTML.hs

@@ -21,6 +21,7 @@ data MdToken
   | Header HeaderLevel MdToken
   | Para MdToken
   | Line [MdToken]
+  | SingleNewline -- A single newline is rendered as a space.
   | Linebreak
   | HorizontalRule
   | Blockquote MdToken
@@ -42,6 +43,7 @@ instance Show MdToken where
   show (Para token) = "<p>" ++ show token ++ "</p>"
   show (Line tokens) = concat (map show tokens)
   show Linebreak = "<br>"
+  show SingleNewline = " "
   show HorizontalRule = "---------"
   show (Blockquote token) = "BLOCK" ++ show token
   show (UnordList tokens) = "UNORD" ++ concat (map show tokens)
@@ -87,12 +89,11 @@ lineToList (Line tokens) = tokens
 parseHeader :: ReadP MdToken
 parseHeader = do
   skipSpaces
-  headers <- many1 mustBeHash
+  headers <- munch1 (== '#')
   when
     ((length headers) > 6)
     pfail
-  _ <- string " "
---  text <- manyTill (get) ((string "\n") <|> (eof >> return ""))-- Parse until EOL or EOF
+  skipSpaces
   text <- munch1 (/= '\n')
   Text.ParserCombinators.ReadP.optional (char '\n')
   let parsedText = fst $ leftmostLongestParse parseLine text
@@ -128,6 +129,11 @@ parseLinebreak = do
   char '\n'
   return Linebreak
 
+parseSingleNewline :: ReadP MdToken
+parseSingleNewline = do
+  char '\n'
+  return SingleNewline
+
 -- Parse a regular string as a Unit.
 parseString :: ReadP MdToken
 parseString = do
@@ -136,7 +142,7 @@ parseString = do
   return (Unit (firstChar : text))
 
 lineParsers :: [ReadP MdToken]
-lineParsers = [parseLinebreak, parseBold, parseItalic, parseString] -- A 'line' doesn't include a 'header'
+lineParsers = [parseLinebreak, parseSingleNewline, parseBold, parseItalic, parseString] -- A 'line' doesn't include a 'header'
 
 -- List of all parsers
 allParsers :: [ReadP MdToken]
@@ -154,7 +160,6 @@ parseLine = do
   remaining <- look
   when (null remaining) pfail
   parsed <- parseMany parseLineToken
-  --         traceM $ show parsed
   return (Line parsed)
 
 -- Parse a paragraph, which is a 'Line' (can span multiple actual lines), separated by double-newlines.

src/Test.hs

@@ -9,9 +9,9 @@ check_equal desc expected actual = TestCase (assertEqual desc expected actual)
 convert :: String -> String
 convert md = show . fst $ leftmostLongestParse parseDocument md
 
-headerTests = TestList
-      [
-         check_equal "Should convert H1 heading" "<h1>Hello</h1>" (convert "# Hello"),
+headerTests =
+  TestList
+    [ check_equal "Should convert H1 heading" "<h1>Hello</h1>" (convert "# Hello"),
       check_equal "Should convert H2 heading" "<h2>Hello</h2>" (convert "## Hello"),
       check_equal "Should convert H3 heading" "<h3>Hello</h3>" (convert "### Hello"),
       check_equal "Should convert H4 heading" "<h4>Hello</h4>" (convert "#### Hello"),
@@ -19,24 +19,24 @@ headerTests = TestList
       check_equal "Should convert H6 heading" "<h6>Hello</h6>" (convert "###### Hello")
     ]
 
-boldTests = TestList
-   [
-         check_equal "Should convert bold" "<p><b>Hello</b></p>" (convert "__Hello__"),
+boldTests =
+  TestList
+    [ check_equal "Should convert bold" "<p><b>Hello</b></p>" (convert "__Hello__"),
       check_equal "Should convert italic" "<p><i>Hello</i></p>" (convert "_Hello_"),
       check_equal "Should convert bold and italic in a sentence" "<p>It <i>is</i> a <b>wonderful</b> day</p>" (convert "It _is_ a __wonderful__ day")
     ]
 
-integrationTests = TestList
-    [
-        check_equal "Integration 1" "<h1>Sample Markdown</h1><p>This is some basic, sample markdown.</p><h2><b>Second</b> <i>Heading</i></h2>" (convert "# Sample Markdown\n\n This is some basic, sample markdown.\n\n  ## __Second__ _Heading_"),
+integrationTests =
+  TestList
+    [ check_equal "Integration 1" "<h1>Sample Markdown</h1><p>This is some basic, sample markdown.</p><h2><b>Second</b> <i>Heading</i></h2>" (convert "# Sample Markdown\n\n This is some basic, sample markdown.\n\n  ## __Second__ _Heading_"),
       check_equal "Integration 2" "<p><b>Hello</b> <i>World</i></p>" (convert "__Hello__\n_World_"),
-        check_equal "Integration 3" "<h1>Hello</h1><p>World</p>" (convert "# Hello\nWorld")
+      check_equal "Integration 3" "<h1>Hello</h1><p>World</p>" (convert "# Hello\nWorld"),
+      check_equal "Integration 4" "<h1>Hello</h1>" (convert "# Hello\n")
     ]
 
-
-tests = TestList
-   [
-      headerTests,
+tests =
+  TestList
+    [ headerTests,
       boldTests,
       integrationTests
     ]