Got recursive parsing working

app/Main.hs

@@ -3,12 +3,17 @@ module Main where
 import Text.ParserCombinators.ReadP
 import Control.Monad
 import Control.Applicative
+import Text.Printf
+import Debug.Trace
 
 type HeaderLevel = Int
 
 newtype URL = URL {getUrl :: String}
 newtype ImgPath = ImgPath {getPath :: String}
 
+parseMany :: ReadP a -> ReadP [a]
+parseMany = Text.ParserCombinators.ReadP.many
+
 data MdToken = Header HeaderLevel MdToken
              | Para [MdToken]
              | Linebreak
@@ -18,11 +23,11 @@ data MdToken = Header HeaderLevel MdToken
              | OrdList [MdToken]
              | Code String
              | Codeblock String
-             | Link [MdToken] URL
-             | Image [MdToken] ImgPath
-             | Bold [MdToken]
-             | Italic [MdToken]
-             | Strikethrough [MdToken]
+             | Link MdToken URL
+             | Image MdToken ImgPath
+             | Bold MdToken
+             | Italic MdToken
+             | Strikethrough MdToken
              | Unit String
 
 -- Deriving Show for MdToken
@@ -34,14 +39,14 @@ instance Show MdToken where
     show (Blockquote token) = "BLOCK" ++ show token
     show (UnordList tokens) = "UNORD" ++ concat(map show tokens)
     show (OrdList tokens) = "ORD" ++ concat(map show tokens)
-    show (Code code) = concat(map show code)
-    show (Codeblock code) = concat(map show code)
-    show (Link txt url) = "<a href=" ++ (getUrl url) ++ ">" ++ concat(map show txt) ++ "</a>"
-    show (Image txt path) = "<img src=" ++ (getPath path) ++ ">" ++ concat(map show txt) ++ "</img>"
-    show (Bold tokens) = "<b>" ++ concat(map show tokens) ++ "</b>"
-    show (Italic tokens) = "<i>" ++ concat(map show tokens) ++ "</i>"
-    show (Strikethrough tokens) = "<s>" ++ concat (map show tokens) ++ "</s>"
-    show (Unit unit) = show unit
+    show (Code code) = show code
+    show (Codeblock code) = show code
+    show (Link txt url) = "<a href=" ++ (getUrl url) ++ ">" ++ show txt ++ "</a>"
+    show (Image txt path) = "<img src=" ++ (getPath path) ++ ">" ++ show txt ++ "</img>"
+    show (Bold token) = "<b>" ++ show token ++ "</b>"
+    show (Italic token) = "<i>" ++ show token ++ "</i>"
+    show (Strikethrough token) = "<s>" ++ show token ++ "</s>"
+    show (Unit unit) = printf "%s" unit
 
 
 
@@ -61,21 +66,38 @@ parseHeader = do
         when ((length headers) > 6)
             pfail
         _ <- string " "
-        text <- munch1 (const True) -- Parse until EOL
-        return (Header (length headers) text)
+        text <- munch1 (\x -> x /= '\n') -- Parse until EOL
+--        traceM text
+        let allParsedText = readP_to_S parsePara text
+        let parsedText = fst . last $ allParsedText
+        return (Header (length headers) parsedText)
                 
 parseBold :: ReadP MdToken
 parseBold = do
         _ <- string "__" <|> string "**"
         text <- munch1 (\x -> x /= '_' && x /= '*') -- Parse until first asterisk/underscore
+ --       traceM text
         _ <- char '_' <|> char '*' -- Throw away the second asterisk/underscore
-        return (Bold text)
+        let parsedText = fst . last $ readP_to_S parsePara text
+        return (Bold parsedText)
 
+parseString :: ReadP MdToken
+parseString = do
+         text <- munch1 (\x -> not (elem x "#*_["))
+   --      traceM text
+         return (Unit text)
 
-parseMain :: String -> []MdToken
+parseLine :: ReadP MdToken
+parseLine = choice [parseHeader,parseBold,parseString]
 
-parseMain 
+parsePara :: ReadP MdToken
+parsePara =  do
+         parsed <- parseMany parseLine
+--         traceM $ show parsed
+         return (Para parsed)
             
 
 main :: IO ()
-main = putStrLn "Hello, Haskell!"
+main = do
+   let res = readP_to_S parsePara "## Hello **world**"
+   putStrLn (show res)