gistfile1.txt

data FileOrDir = File | Dir
-- Valid path
data Path :: FileOrDir -> * where
  F :: Text -> Path File
  D :: Text -> Path Dir
data Exists :: FileOrDir -> * where
  FE :: Exists File
  DE :: Exists Dir

data NIO 

fileName  :: Text -> Maybe Name
pathFile  :: Text -> Maybe (Path File)
pathDir   :: Text -> Maybe (Path Dir)
:: Path Dir -> Name -> Path Dir
:: Path Dir -> Name -> Path File
parent :: Path a -> Maybe (Path Dir) -- Nothing for root dir
-- volumes?


  Run with a temporary path that has NO file (e.g. no meta or contents) when created.
  The directory of the file exists.
  Whatever bytes/meta are placed here are recycled on scope end.
withTempFile :: (Path File -> m a) -> m LowlevelError a

  Run with a temporary path that has NO file (e.g. no meta or contents) when created.
  Whatever bytes/meta are placed here are recycled on scope end.
withTempDir :: (Path Dir -> m a) -> m LowlevelError a


  There always create parents if necessary.
createDirIn :: Path Dir -> Name -> NIO (DirExits|Exists FileOrDir|LowlevelError) ()
createDir   :: Path a -> NIO (Exists a + LowlevelError) ()
remove      :: Path a -> NIO (WrongFileOrDirType + NothingToRemove + LowlevelError) ()