-- |The main loop that extracts the commands and parses them into actions.
recurs :: IO Turtle -> IO Turtle
recurs iot = do
    t  <- iot
    recurs $ (words <$> getLine) >>= parse_ln t

-- |Parse a line of user input or file input.
recurs :: IO Turtle -> IO Turtle
recurs iot = do
    t  <- iot
    recurs $ (words <$> getLine) >>= parse_ln t

-- |Parse a line of user input or file input.
recurs iot = do
    t  <- iot
    recurs $ (words <$> getLine) >>= parse_ln t

-- |Parse a line of user input or file input.