Made some changes

app/Main.hs

@@ -1,27 +1,8 @@
 module Main where
 
 import MdToHTML
-import System.Environment
-import System.IO
-
-readLinesHelper :: [String] -> IO [String]
-readLinesHelper xs = do
-  done <- isEOF
-  if done
-    then return xs
-    else do
-      line <- getLine
-      let xs' = line : xs
-      readLinesHelper xs'
-
-readLines :: IO [String]
-readLines = fmap reverse $ readLinesHelper []
 
 main :: IO ()
 main = do
-  args <- getArgs
-  fileContents <- case args of
-    [] -> getContents
-    x : _ -> readFile x
-  let res = fst $ leftmostLongestParse parseDocument fileContents
-  print res
+   let res = fst $ leftmostLongestParse parseDocument "# _Hello_\n"
+   putStrLn (show res)

md-to-html.cabal

@@ -67,6 +67,10 @@ executable md-to-html-runner
     -- .hs or .lhs file containing the Main module.
     main-is:          Main.hs
 
+    -- Modules included in this executable, other than Main.
+    other-modules:
+        MdToHTML
+        MdToHtmlTest
 
     -- LANGUAGE extensions used by modules in this package.
     -- other-extensions:

src/MdToHTML.hs

@@ -58,7 +58,7 @@ instance Show MdToken where
   show (Code code) = "<code>" ++ show code ++ "</code>"
   show (Codeblock code) = show code
   show (Link txt url) = "<a href=\"" ++ getUrl url ++ "\">" ++ show txt ++ "</a>"
-  show (Image txt imgPath) = "<img src=\"" ++ getPath imgPath ++ "\"" ++ " alt=\"" ++ show txt ++ "\" />"
+  show (Image txt imgPath) = "<img src=" ++ getPath imgPath ++ ">" ++ show txt ++ "</img>"
   show (Bold token) = "<b>" ++ show token ++ "</b>"
   show (Italic token) = "<i>" ++ show token ++ "</i>"
   show (Strikethrough token) = "<s>" ++ show token ++ "</s>"
@@ -88,9 +88,9 @@ leftmostLongestParse parser input =
         Nothing -> (mempty, mempty)
         Just x -> x
 
-specialChars = "\n\\`*_{}[]()<>#+|"
+specialChars = "\\#*_[\n`"
 
-escapableChars = "-~!." ++ specialChars
+escapableChars = '~' : specialChars
 
 -- Makes a parser greedy. Instead of returning all possible parses, only the longest one is returned.
 greedyParse :: ReadP a -> ReadP [a]
@@ -120,6 +120,16 @@ fallthroughParser :: [ReadP a] -> ReadP a
 fallthroughParser [x] = x
 fallthroughParser (x : xs) = x <++ fallthroughParser xs
 
+myMany :: (Monoid a) => ReadP a -> ReadP [a]
+myMany p = do
+  remaining <- look
+  case remaining of
+    [] -> return []
+    _ -> return [] +++ myMany1 p
+
+myMany1 :: (Monoid a) => ReadP a -> ReadP [a]
+myMany1 p = liftM2 (:) p (myMany p)
+
 -- ---------------
 
 -- Parse a markdown header, denoted by 1-6 #'s followed by some text, followed by EOL.
@@ -143,19 +153,25 @@ parseBold = parseBoldWith "**" <|> parseBoldWith "__"
   where
     parseBoldWith delim = do
       string delim
-      inside <- greedyParse1 parseLineToken
+      inside <- myMany1 parseLineToken
       string delim
       return (Bold (Line inside))
 
 -- Parse italic text
 parseItalic :: ReadP MdToken
-parseItalic = parseItalicWith "*" <|> parseItalicWith "_"
+parseItalic = parseItalicWith '*' <|> parseItalicWith '_'
   where
     parseItalicWith delim = do
-      string delim
-      inside <- greedyParse1 parseLineToken
-      string delim
+      exactlyOnce delim
+      inside <- myMany1 parseLineToken
+      exactlyOnce delim
       return (Italic (Line inside))
+    exactlyOnce ch = do
+      char ch
+      remaining <- look
+      case remaining of
+        [] -> return ch
+        x : xs -> if x == ch then pfail else return ch
 
 -- Parse strikethrough text
 parseStrikethrough :: ReadP MdToken
@@ -194,17 +210,6 @@ parseSingleNewline = do
   char '\n'
   return SingleNewline
 
-parseImage :: ReadP MdToken
-parseImage = do
-  char '!'
-  char '['
-  altText <- many1 (parseEscapedChar <++ parseUnit)
-  char ']'
-  char '('
-  path <- many1 get
-  char ')'
-  return $ Image (Line altText) (ImgPath path)
-
 -- Parse an escaped character
 parseEscapedChar :: ReadP MdToken
 parseEscapedChar = do
@@ -215,7 +220,8 @@ parseEscapedChar = do
 -- Parse a character as a Unit.
 parseUnit :: ReadP MdToken
 parseUnit = do
-  text <- satisfy (`notElem` specialChars)
+  -- text <- satisfy (`notElem` specialChars)
+  text <- get
   return (Unit [text])
 
 lineParsers :: [ReadP MdToken]
@@ -224,7 +230,6 @@ lineParsers =
     parseSingleNewline,
     parseEscapedChar,
     parseCode,
-    parseImage,
     parseBold,
     parseItalic,
     parseStrikethrough,
@@ -237,7 +242,6 @@ listLineParsers =
   [ parseLinebreak,
     parseEscapedChar,
     parseCode,
-    parseImage,
     parseBold,
     parseItalic,
     parseStrikethrough,
@@ -262,7 +266,7 @@ parseLine :: ReadP MdToken
 parseLine = do
   skipSpaces
   -- Fail if we have reached the end of the document.
-  parsed <- manyTill parseLineToken eof
+  parsed <- myMany1 parseLineToken
   return (Line parsed)
 
 -- Parse a paragraph, which is a 'Line' (can span multiple actual lines), separated by double-newlines.

src/MdToHtmlTest.hs

@@ -22,6 +22,7 @@ headerTests =
 boldTests =
   TestList
     [ check_equal "Should convert bold" "<p><b>Hello</b></p>" (convert "__Hello__"),
+      check_equal " Should not convert incomplete bold" "<p>**Hello</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"),
       check_equal "Should convert nested bold and italic" "<p><b>Bold then <i>Italic</i></b></p>" (convert "**Bold then *Italic***"),
@@ -97,13 +98,7 @@ codeTests =
   TestList
     [ check_equal "Code by itself" "<p><code>Hello world!</code></p>" (convert "`Hello world!`"),
       check_equal "Code in a paragraph" "<p>The following <code>text</code> is code</p>" (convert "The following `text` is code"),
-      check_equal "Code across paragraphs (shouldn't work" "<p></p><p></p>" (convert "`Incomplete\n\nCode`") -- At the moment, this is just treated as a syntax error, so nothing is rendered.
-    ]
-
-imageTests =
-  TestList
-    [ check_equal "Image by itself" "<p><img src=\"img.png\" alt=\"Image 1\" /></p>" (convert "![Image 1](img.png)"),
-      check_equal "Image with text" "<p>This is an image <img src=\"img.png\" alt=\"Image 1\" /></p>" (convert "This is an image ![Image 1](img.png)")
+      check_equal "Code across paragraphs (shouldn't work" "<p>`Incomplete</p><p>Code`</p>" (convert "`Incomplete\n\nCode`")
     ]
 
 integrationTests =
@@ -140,7 +135,6 @@ tests =
       blockquoteTests,
       unorderedListTests,
       orderedListTests,
-      imageTests,
       codeTests,
       integrationTests
     ]