matchMaybe.hs

matchMaybe :: forall a. TomlBiMap a AnyValue -> Key -> TomlCodec (Maybe a)
matchMaybe Toml.BiMap {forward, backward} key = Toml.Codec input output
  where
    input :: Toml.TomlEnv (Maybe a)
    input toml = case HashMap.lookup key (Toml.tomlPairs toml) of
      Nothing -> pure Nothing
      Just anyVal -> pure <$> Toml.whenLeftBiMapError key (backward anyVal) pure

    output :: Maybe a -> Toml.TomlState (Maybe a)
    output Nothing = pure Nothing
    output (Just a) = do
      anyVal <- Toml.eitherToTomlState $ forward a
      Just a <$ modify (insertKeyAnyVal key anyVal)


--
-- Using match
--

-- >>> Toml.decode (match Toml._ZonedTime "time") ""
-- Left [KeyNotFound ("time" :| [])]
--
-- >>> Toml.decode (match Toml._ZonedTime "time") "time = 1"
-- Left [BiMapError ("time" :| []) (WrongValue (MatchError {valueExpected = TZoned, valueActual = Integer 1}))]
--
-- >>> Toml.decode (match Toml._ZonedTime "time") "time = \"some text\""
-- Left [BiMapError ("time" :| []) (WrongValue (MatchError {valueExpected = TZoned, valueActual = Text "some text"}))]
--
-- >>> Toml.decode (match Toml._ZonedTime "time") "time = '2022-08-22T10:38:45Z'"
-- Left [BiMapError ("time" :| []) (WrongValue (MatchError {valueExpected = TZoned, valueActual = Text "2022-08-22T10:38:45Z"}))]
--
-- >>> Toml.decode (match Toml._ZonedTime "time") "time = 2022-08-22T10:38:45Z"
-- Right 2022-08-22 10:38:45 +0000

--
-- Using match and dioptional
--

-- >>> Toml.decode (Toml.dioptional $ match Toml._ZonedTime "time") ""
-- Right Nothing
--
-- >>> Toml.decode (Toml.dioptional $ match Toml._ZonedTime "time") "time = 1"
-- Right Nothing
--
-- >>> Toml.decode (Toml.dioptional $ match Toml._ZonedTime "time") "time = \"some text\""
-- Right Nothing
--
-- >>> Toml.decode (Toml.dioptional $ match Toml._ZonedTime "time") "time = '2022-08-22T10:38:45Z'"
-- Right Nothing
--
-- >>> Toml.decode (Toml.dioptional $ match Toml._ZonedTime "time") "time = 2022-08-22T10:38:45Z"
-- Right (Just 2022-08-22 10:38:45 +0000)

--
-- Using matchMaybe
--

-- >>> Toml.decode (matchMaybe Toml._ZonedTime "time") ""
-- Right Nothing
--
-- >>> Toml.decode (matchMaybe Toml._ZonedTime "time") "time = 1"
-- Left [BiMapError ("time" :| []) (WrongValue (MatchError {valueExpected = TZoned, valueActual = Integer 1}))]
--
-- >>> Toml.decode (matchMaybe Toml._ZonedTime "time") "time = \"some text\""
-- Left [BiMapError ("time" :| []) (WrongValue (MatchError {valueExpected = TZoned, valueActual = Text "some text"}))]
--
-- >>> Toml.decode (matchMaybe Toml._ZonedTime "time") "time = '2022-08-22T10:38:45Z'"
-- Left [BiMapError ("time" :| []) (WrongValue (MatchError {valueExpected = TZoned, valueActual = Text "2022-08-22T10:38:45Z"}))]
--
-- >>> Toml.decode (matchMaybe Toml._ZonedTime "time") "time = 2022-08-22T10:38:45Z"
-- Right (Just 2022-08-22 10:38:45 +0000)