Data.Aeson.Micro

Minimal JavaScript Object Notation (JSON) support as per RFC 8259.

This API provides a subset (with a couple of divergences; see below) of aeson API but puts the emphasis on simplicity rather than performance and features.

The ToJSON and FromJSON instances are intended to have an encoding compatible with aeson's encoding.

Limitations and divergences from aeson's API

In order to reduce the dependency footprint and keep the code simpler, the following divergences from the aeson API have to be made:

• There are no FromJSON/ToJSON instances for Char & String.
• The type synonym (& the constructor of the same name) Object uses containers's Map rather than a HashMap unordered-containers.
• Array is represented by an ordinary list rather than a Vector from the vector package.
• Number uses Double instead of Scientific

Core JSON types

data Value

A JSON value represented as a Haskell value.

Constructors

Object !Object

Array [Value]

String !Text

Number !Double

Bool !Bool

Null

Instances

Eq Value

Methods

(==) :: Value -> Value -> Bool

(/=) :: Value -> Value -> Bool

Data Value

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Value -> c Value

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Value

toConstr :: Value -> Constr

dataTypeOf :: Value -> DataType

dataCast1 :: Typeable (* -> *) t => (forall d. Data d => c (t d)) -> Maybe (c Value)

dataCast2 :: Typeable (* -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Value)

gmapT :: (forall b. Data b => b -> b) -> Value -> Value

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Value -> r

gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Value -> r

gmapQ :: (forall d. Data d => d -> u) -> Value -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> Value -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Value -> m Value

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Value -> m Value

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Value -> m Value

Read Value

Methods

readsPrec :: Int -> ReadS Value

readList :: ReadS [Value]

readPrec :: ReadPrec Value

readListPrec :: ReadPrec [Value]

Show Value

Methods

showsPrec :: Int -> Value -> ShowS

show :: Value -> String

showList :: [Value] -> ShowS

IsString Value

Methods

fromString :: String -> Value

Generic Value

Associated Types

type Rep Value :: * -> *

Methods

from :: Value -> Rep Value x

to :: Rep Value x -> Value

NFData Value

Methods

rnf :: Value -> ()

FromJSON Value

Methods

parseJSON :: Value -> Parser Value

ToJSON Value

Methods

toJSON :: Value -> Value

type Rep Value

type Rep Value = D1 * (MetaData "Value" "Data.Aeson.Micro" "microaeson-0.1.0.0-4H0jW4FLu0lBN2s49mqfPU" False) ((:+:) * ((:+:) * (C1 * (MetaCons "Object" PrefixI False) (S1 * (MetaSel (Nothing Symbol) NoSourceUnpackedness SourceStrict DecidedStrict) (Rec0 * Object))) ((:+:) * (C1 * (MetaCons "Array" PrefixI False) (S1 * (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 * [Value]))) (C1 * (MetaCons "String" PrefixI False) (S1 * (MetaSel (Nothing Symbol) NoSourceUnpackedness SourceStrict DecidedStrict) (Rec0 * Text))))) ((:+:) * (C1 * (MetaCons "Number" PrefixI False) (S1 * (MetaSel (Nothing Symbol) NoSourceUnpackedness SourceStrict DecidedStrict) (Rec0 * Double))) ((:+:) * (C1 * (MetaCons "Bool" PrefixI False) (S1 * (MetaSel (Nothing Symbol) NoSourceUnpackedness SourceStrict DecidedStrict) (Rec0 * Bool))) (C1 * (MetaCons "Null" PrefixI False) (U1 *)))))

type Object = Map Text Value

A JSON "object" (key/value map).

type Pair = (Text, Value)

A key/value pair for an Object

Constructors

(.=) :: ToJSON v => Text -> v -> Pair infixr 8

A key-value pair for encoding a JSON object.

object :: [Pair] -> Value

Create a Value from a list of name/value Pairs.

emptyArray :: Value

The empty JSON Array (i.e. []).

emptyObject :: Value

The empty JSON Object (i.e. {}).

Accessors

(.:) :: FromJSON a => Object -> Text -> Parser a

(.:?) :: FromJSON a => Object -> Text -> Parser (Maybe a)

(.:!) :: FromJSON a => Object -> Text -> Parser (Maybe a)

(.!=) :: Parser (Maybe a) -> a -> Parser a

Encoding and decoding

encode :: ToJSON a => a -> ByteString

Serialise value as JSON/UTF-8-encoded lazy ByteString

encodeStrict :: ToJSON a => a -> ByteString

Serialise value as JSON/UTF-8-encoded strict ByteString

encodeToBuilder :: ToJSON a => a -> Builder

Serialise value as JSON/UTF8-encoded Builder

decodeStrict :: FromJSON a => ByteString -> Maybe a

Decode a single JSON document

decode :: FromJSON a => ByteString -> Maybe a

Decode a single JSON document

decodeStrictN :: FromJSON a => ByteString -> Maybe [a]

Decode multiple concatenated JSON documents

Prism-style parsers

withObject :: String -> (Object -> Parser a) -> Value -> Parser a

withText :: String -> (Text -> Parser a) -> Value -> Parser a

withArray :: String -> ([Value] -> Parser a) -> Value -> Parser a

withNumber :: String -> (Double -> Parser a) -> Value -> Parser a

withBool :: String -> (Bool -> Parser a) -> Value -> Parser a

Type conversion

class FromJSON a where

A type that JSON can be deserialised into

Minimal complete definition

parseJSON

Methods

parseJSON :: Value -> Parser a

Decode a JSON value into a native Haskell type

Instances

FromJSON Bool

Methods

parseJSON :: Value -> Parser Bool

FromJSON Double

Methods

parseJSON :: Value -> Parser Double

FromJSON Float

Methods

parseJSON :: Value -> Parser Float

FromJSON Int

Methods

parseJSON :: Value -> Parser Int

FromJSON Int8

Methods

parseJSON :: Value -> Parser Int8

FromJSON Int16

Methods

parseJSON :: Value -> Parser Int16

FromJSON Int32

Methods

parseJSON :: Value -> Parser Int32

FromJSON Int64

Methods

parseJSON :: Value -> Parser Int64

FromJSON Integer

Methods

parseJSON :: Value -> Parser Integer

FromJSON Ordering

Methods

parseJSON :: Value -> Parser Ordering

FromJSON Word

Methods

parseJSON :: Value -> Parser Word

FromJSON Word8

Methods

parseJSON :: Value -> Parser Word8

FromJSON Word16

Methods

parseJSON :: Value -> Parser Word16

FromJSON Word32

Methods

parseJSON :: Value -> Parser Word32

FromJSON Word64

Methods

parseJSON :: Value -> Parser Word64

FromJSON ()

Methods

parseJSON :: Value -> Parser ()

FromJSON Text

Methods

parseJSON :: Value -> Parser Text

FromJSON Text

Methods

parseJSON :: Value -> Parser Text

FromJSON Value

Methods

parseJSON :: Value -> Parser Value

FromJSON a => FromJSON [a]

Methods

parseJSON :: Value -> Parser [a]

FromJSON a => FromJSON (Maybe a)

Methods

parseJSON :: Value -> Parser (Maybe a)

(FromJSON a, FromJSON b) => FromJSON (a, b)

Methods

parseJSON :: Value -> Parser (a, b)

FromJSON v => FromJSON (Map Text v)

Methods

parseJSON :: Value -> Parser (Map Text v)

(FromJSON a, FromJSON b, FromJSON c) => FromJSON (a, b, c)

Methods

parseJSON :: Value -> Parser (a, b, c)

(FromJSON a, FromJSON b, FromJSON c, FromJSON d) => FromJSON (a, b, c, d)

Methods

parseJSON :: Value -> Parser (a, b, c, d)

data Parser a

JSON Parser Monad used by FromJSON

Instances

Monad Parser

Methods

(>>=) :: Parser a -> (a -> Parser b) -> Parser b

(>>) :: Parser a -> Parser b -> Parser b

return :: a -> Parser a

fail :: String -> Parser a

Functor Parser

Methods

fmap :: (a -> b) -> Parser a -> Parser b

(<$) :: a -> Parser b -> Parser a

Applicative Parser

Methods

pure :: a -> Parser a

(<*>) :: Parser (a -> b) -> Parser a -> Parser b

liftA2 :: (a -> b -> c) -> Parser a -> Parser b -> Parser c

(*>) :: Parser a -> Parser b -> Parser b

(<*) :: Parser a -> Parser b -> Parser a

parseMaybe :: (a -> Parser b) -> a -> Maybe b

Run Parser.

A common use-case is parseMaybe parseJSON.

class ToJSON a where

A type that can be converted to JSON.

Minimal complete definition

toJSON

Methods

toJSON :: a -> Value

Convert a Haskell value to a JSON-friendly intermediate type.

Instances

ToJSON Bool

Methods

toJSON :: Bool -> Value

ToJSON Double

Methods

toJSON :: Double -> Value

ToJSON Float

Methods

toJSON :: Float -> Value

ToJSON Int

Methods

toJSON :: Int -> Value

ToJSON Int8

Methods

toJSON :: Int8 -> Value

ToJSON Int16

Methods

toJSON :: Int16 -> Value

ToJSON Int32

Methods

toJSON :: Int32 -> Value

ToJSON Int64

Possibly lossy due to conversion to Double

Methods

toJSON :: Int64 -> Value

ToJSON Integer

Possibly lossy due to conversion to Double

Methods

toJSON :: Integer -> Value

ToJSON Word

Methods

toJSON :: Word -> Value

ToJSON Word8

Methods

toJSON :: Word8 -> Value

ToJSON Word16

Methods

toJSON :: Word16 -> Value

ToJSON Word32

Methods

toJSON :: Word32 -> Value

ToJSON Word64

Possibly lossy due to conversion to Double

Methods

toJSON :: Word64 -> Value

ToJSON ()

Methods

toJSON :: () -> Value

ToJSON Text

Methods

toJSON :: Text -> Value

ToJSON Text

Methods

toJSON :: Text -> Value

ToJSON Value

Methods

toJSON :: Value -> Value

ToJSON a => ToJSON [a]

Methods

toJSON :: [a] -> Value

ToJSON a => ToJSON (Maybe a)

Methods

toJSON :: Maybe a -> Value

(ToJSON a, ToJSON b) => ToJSON (a, b)

Methods

toJSON :: (a, b) -> Value

ToJSON v => ToJSON (Map Text v)

Methods

toJSON :: Map Text v -> Value

(ToJSON a, ToJSON b, ToJSON c) => ToJSON (a, b, c)

Methods

toJSON :: (a, b, c) -> Value

(ToJSON a, ToJSON b, ToJSON c, ToJSON d) => ToJSON (a, b, c, d)

Methods

toJSON :: (a, b, c, d) -> Value