[Haskell-cafe] Need help with learning Parsec

19 Jul 2012

      Dear gentle Haskellers,

I was trying to whet my Haskell by trying out Parsec today to try and parse
out XML. Here's the code I cam up with -

I wanted some help with the "gettext" parser that I've written. I had to do
a dummy "char '  ') in there just to satisfy the "many" used in the xml
parser. I'd appreciate it very much if someone could give me some feedback.

data XML =  Node String [XML]
          | Body String deriving Show

gettext = do
             x <- many (letter <|> digit )
             if (length x) > 0 then
                return (Body x)
             else (char ' ' >> (return $ Body ""))

xml :: Parser XML
xml = do {
          name <- openTag
        ; innerXML <- many innerXML
        ; endTag name
        ; return (Node name innerXML)
         }

innerXML = do
         x <- (try xml <|> gettext)
         return x

openTag :: Parser String
openTag = do
        char '<'
        content <- many (noneOf ">")
        char '>'
        return content

endTag :: String -> Parser String
endTag str = do
        char '<'
        char '/'
        string str
        char '>'
        return str

h1 = parse xml "" "<a>A</a>"
h2 = parse xml "" "<a><b>A</b></a>"
h3 = parse xml "" "<a><b><c></c></b></a>"
h4 = parse xml "" "<a><b></b><c></c></a>"

Regards,
Kashyap

[Haskell-cafe] Need help with learning Parsec

C K Kashyap