Copyright	(C) 2015-2016 Oleg Grenrus
License	BSD3
Maintainer	Oleg Grenrus <oleg.grenrus@iki.fi>
Safe Haskell	None
Language	Haskell2010

Data.Aeson.Extra.CollapsedList

Description

Synopsis

newtype CollapsedList f a = CollapsedList (f a)
getCollapsedList :: CollapsedList f a -> f a
parseCollapsedList :: (FromJSON a, FromJSON1 f, Alternative f) => Object -> Text -> Parser (f a)

Documentation

newtype CollapsedList f a Source #

Collapsed list, singleton is represented as the value itself in JSON encoding.

λ > decode "null" :: Maybe (CollapsedList [Int] Int)
Just (CollapsedList [])
λ > decode "42" :: Maybe (CollapsedList [Int] Int)
Just (CollapsedList [42])
λ > decode "[1, 2, 3]" :: Maybe (CollapsedList [Int] Int)
Just (CollapsedList [1,2,3])

λ > encode (CollapsedList ([] :: [Int]))
"null"
λ > encode (CollapsedList ([42] :: [Int]))
"42"
λ > encode (CollapsedList ([1, 2, 3] :: [Int]))
"[1,2,3]"

Documentation rely on f Alternative instance behaving like lists'.

Constructors

CollapsedList (f a)

Instances

Instances details

Functor f => Functor (CollapsedList f) Source #
Instance details Defined in Data.Aeson.Extra.CollapsedList Methods fmap :: (a -> b) -> CollapsedList f a -> CollapsedList f b # (<$) :: a -> CollapsedList f b -> CollapsedList f a #
Foldable f => Foldable (CollapsedList f) Source #
Instance details Defined in Data.Aeson.Extra.CollapsedList Methods fold :: Monoid m => CollapsedList f m -> m # foldMap :: Monoid m => (a -> m) -> CollapsedList f a -> m # foldMap' :: Monoid m => (a -> m) -> CollapsedList f a -> m # foldr :: (a -> b -> b) -> b -> CollapsedList f a -> b # foldr' :: (a -> b -> b) -> b -> CollapsedList f a -> b # foldl :: (b -> a -> b) -> b -> CollapsedList f a -> b # foldl' :: (b -> a -> b) -> b -> CollapsedList f a -> b # foldr1 :: (a -> a -> a) -> CollapsedList f a -> a # foldl1 :: (a -> a -> a) -> CollapsedList f a -> a # toList :: CollapsedList f a -> [a] # null :: CollapsedList f a -> Bool # length :: CollapsedList f a -> Int # elem :: Eq a => a -> CollapsedList f a -> Bool # maximum :: Ord a => CollapsedList f a -> a # minimum :: Ord a => CollapsedList f a -> a # sum :: Num a => CollapsedList f a -> a # product :: Num a => CollapsedList f a -> a #
Traversable f => Traversable (CollapsedList f) Source #
Instance details Defined in Data.Aeson.Extra.CollapsedList Methods traverse :: Applicative f0 => (a -> f0 b) -> CollapsedList f a -> f0 (CollapsedList f b) # sequenceA :: Applicative f0 => CollapsedList f (f0 a) -> f0 (CollapsedList f a) # mapM :: Monad m => (a -> m b) -> CollapsedList f a -> m (CollapsedList f b) # sequence :: Monad m => CollapsedList f (m a) -> m (CollapsedList f a) #
(ToJSON1 f, Foldable f) => ToJSON1 (CollapsedList f) Source #
Instance details Defined in Data.Aeson.Extra.CollapsedList Methods liftToJSON :: (a -> Value) -> ([a] -> Value) -> CollapsedList f a -> Value # liftToJSONList :: (a -> Value) -> ([a] -> Value) -> [CollapsedList f a] -> Value # liftToEncoding :: (a -> Encoding) -> ([a] -> Encoding) -> CollapsedList f a -> Encoding # liftToEncodingList :: (a -> Encoding) -> ([a] -> Encoding) -> [CollapsedList f a] -> Encoding #
(FromJSON1 f, Alternative f) => FromJSON1 (CollapsedList f) Source #
Instance details Defined in Data.Aeson.Extra.CollapsedList Methods liftParseJSON :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser (CollapsedList f a) # liftParseJSONList :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser [CollapsedList f a] #
Eq (f a) => Eq (CollapsedList f a) Source #
Instance details Defined in Data.Aeson.Extra.CollapsedList Methods (==) :: CollapsedList f a -> CollapsedList f a -> Bool # (/=) :: CollapsedList f a -> CollapsedList f a -> Bool #
Ord (f a) => Ord (CollapsedList f a) Source #
Instance details Defined in Data.Aeson.Extra.CollapsedList Methods compare :: CollapsedList f a -> CollapsedList f a -> Ordering # (<) :: CollapsedList f a -> CollapsedList f a -> Bool # (<=) :: CollapsedList f a -> CollapsedList f a -> Bool # (>) :: CollapsedList f a -> CollapsedList f a -> Bool # (>=) :: CollapsedList f a -> CollapsedList f a -> Bool # max :: CollapsedList f a -> CollapsedList f a -> CollapsedList f a # min :: CollapsedList f a -> CollapsedList f a -> CollapsedList f a #
Read (f a) => Read (CollapsedList f a) Source #
Instance details Defined in Data.Aeson.Extra.CollapsedList Methods readsPrec :: Int -> ReadS (CollapsedList f a) # readList :: ReadS [CollapsedList f a] # readPrec :: ReadPrec (CollapsedList f a) # readListPrec :: ReadPrec [CollapsedList f a] #
Show (f a) => Show (CollapsedList f a) Source #
Instance details Defined in Data.Aeson.Extra.CollapsedList Methods showsPrec :: Int -> CollapsedList f a -> ShowS # show :: CollapsedList f a -> String # showList :: [CollapsedList f a] -> ShowS #
(ToJSON1 f, Foldable f, ToJSON a) => ToJSON (CollapsedList f a) Source #
Instance details Defined in Data.Aeson.Extra.CollapsedList Methods toJSON :: CollapsedList f a -> Value # toEncoding :: CollapsedList f a -> Encoding # toJSONList :: [CollapsedList f a] -> Value # toEncodingList :: [CollapsedList f a] -> Encoding #
(FromJSON1 f, Alternative f, FromJSON a) => FromJSON (CollapsedList f a) Source #
Instance details Defined in Data.Aeson.Extra.CollapsedList Methods parseJSON :: Value -> Parser (CollapsedList f a) # parseJSONList :: Value -> Parser [CollapsedList f a] #

getCollapsedList :: CollapsedList f a -> f a Source #

parseCollapsedList :: (FromJSON a, FromJSON1 f, Alternative f) => Object -> Text -> Parser (f a) Source #

Parses possibly collapsed array value from the object's field.

λ > newtype V = V [Int] deriving (Show)
λ > instance FromJSON V where parseJSON = withObject "V" $ \obj -> V <$> parseCollapsedList obj "value"
λ > decode "{}" :: Maybe V
Just (V [])
λ > decode "{\"value\": null}" :: Maybe V
Just (V [])
λ > decode "{\"value\": 42}" :: Maybe V
Just (V [42])
λ > decode "{\"value\": [1, 2, 3, 4]}" :: Maybe V
Just (V [1,2,3,4])