[Haskell-beginners] Parsing Custom TeX

[Jeffrey Drake]

I am getting frustrated when trying to implement a parser for a minimal
TeX subset. I am essentially trying to implement something that
recognizes \commands (no parameters yet), paragraphs (two newlines), and
text (almost anything else).

The code I have so far is: 

module UnTeX where

import Text.ParserCombinators.Parsec
import Text.ParserCombinators.Parsec.Prim
import Text.ParserCombinators.Parsec.Language
import qualified Text.ParserCombinators.Parsec.Token as T

data UnTeX = Command String
            | Text String
            | Paragraph
        deriving Show


command :: Parser UnTeX
command = do    char '\\'
                cmd <- many1 (letter <|> digit) <?> "command"
                return $ Command cmd

paragraph :: Parser UnTeX
paragraph = do  newline
                newline
                return $ Paragraph

text :: Parser UnTeX
text = do       txt <- many1 (alphaNum <|> space)
                return $ Text txt


I have no illusions that this is probably far from what I actually need
to be doing. But I am finding documentation on all this to be spotty.
The 'parsec.pdf' is 7 years old and code doesn't always work.

Can anyone point me in the right direction? I just want something to
able to do this simply. After an initial version works, I would like to
have commands with parameters - something like
\command[param][param]{body} but need to have something working first.

Thank you for any help you can provide.
Jeffrey.