parse1 :: Parser a -> String -> Maybe a
parse1 p s = case parse p s of
    []      -> Nothing
    (x : _) -> Just x
parse1 :: Parser a -> String -> Maybe a
parse1 p s = case parse p s of
    []      -> Nothing
    (x : _) -> Just x
parse1 p s = case parse p s of
    []      -> Nothing
    (x : _) -> Just x