Stuff

config.ttxt

 -- Example with your sample
vhosts
  nullable.se
    aliases: nullable.se.dev
    redirect: www.nullable.se
    serve: /var/www
 -- Also trivially equivalent to
vhosts
  nullable.se
    aliases
      nullable.se.dev
    redirect
      www.nullable.se
    serve
      /var/www
 -- Expanded to
vhosts
  nullable.se
    serve
      FSDirectory
        directory: /var/www
  nullable.se.dev
    serve
      FSDirectory
        directory: /var/www
  www.nullable.se
    serve
      Redirect: http://nullable.se/

Parser.hs

module Parser
import ImaginaryTTXTParser
import Data.Map

data Serve = Redirect String | FSDirectory String deriving (Show) -- Strings for simplification

data ConfigFile = ConfigFile (Map String Serve) deriving (Show)

vhosts (ConfigFile vhosts') = vhosts'

parseConfigFile :: TTXT -> Maybe ConfigFile
parseConfigFile ttxt = (ConfigFile . fromList) <$> (getOnly "vhosts" ttxt >>= parseVHosts)

parseVHosts :: [TTXT] -> Maybe [(String, Serve)]
parseVHosts ttxt = join $ join $ map optionToList $ map parseVHost ttxt

parseVHost :: TTXT -> Maybe [(String, Serve)]
parseVHost ttxt@(TTXT name _) =
  do serve <- getVHostServe ttxt
     let main = (name, serve)
     (TTXT _ aliases) <- getOnly "aliases" ttxt
     let aliases' = map ((, serve) . name) aliases
     (TTXT _ redirects) <- getOnly "redirects" ttxt
     let redirects' = map ((, Redirect name) . name) redirects
     return $ main ++ aliases' ++ redirects'

getVHostServes :: TTXT -> Maybe Serve
getVHostServes ttxt =
  do serve <- getOnly "serve" ttxt
     if not $ hasChildren serve
       then FSDirectory $ name serve
       else primitiveMakeServe ttxt

primitiveMakeServe :: TTXT -> Maybe Serve
primitiveMakeServe (TTXT "FSDirectory" [TTXT dir []]) = Just $ FSDirectory dir
primitiveMakeServe (TTXT "Redirect" [TTXT url []]) = Just $ Redirect url
primitiveMakeServe _ = Nothing

main =
  do ttxt <- ttxtFromFile "config.ttxt"
     print $ parseConfigFile ttxt