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AppConfig.hs
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AppConfig.hs
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-- |Support for read-only executable application configurations.
module Ros.Internal.Util.AppConfig where
import Control.Monad.Reader
import Control.Concurrent
data ConfigOptions = ConfigOptions { verbosity :: Int }
type Config = ReaderT ConfigOptions IO
getVerbosity :: Config Int
getVerbosity = verbosity `fmap` ask
debug :: String -> Config ()
debug s = do v <- getVerbosity
when (v > 0) (liftIO (putStrLn s))
forkConfig :: Config () -> Config ThreadId
forkConfig c = do r <- ask
liftIO . forkIO $ runReaderT c r
parseAppConfig :: [String] -> (ConfigOptions, [String])
parseAppConfig args
| "-v" `elem` args = (ConfigOptions 1, filter (`notElem` appOpts) args)
| otherwise = (ConfigOptions 0, args)
where appOpts = ["-v"]
configured :: Config a -> Config (IO a)
configured c = ask >>= return . runReaderT c