isPasswordValid :: [Char] -> Either [Char] [Char]
isPasswordValid pwd =
  isPasswordHasNumber pwd >>= isPasswordRightLength
isPasswordValid :: [Char] -> Either [Char] [Char]
isPasswordValid pwd =
  isPasswordHasNumber pwd >>= isPasswordRightLength
isPasswordValid pwd =
  isPasswordHasNumber pwd >>= isPasswordRightLength