proto-lens-jsonpb-0.1.0.0: JSON protobuf encoding for proto-lens

Safe HaskellNone
LanguageHaskell2010

Data.ProtoLens.JSONPB

Contents

Synopsis

Typeclasses

class FromJSONPB a where Source #

FromJSON variant for JSONPB decoding from the Value IR

Methods

parseJSONPB :: Value -> Parser a Source #

parseJSON variant for JSONPB decoders.

Instances
FromJSONPB Bool Source # 
Instance details

Defined in Data.ProtoLens.JSONPB.Class

FromJSONPB Double Source # 
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Defined in Data.ProtoLens.JSONPB.Class

FromJSONPB Float Source # 
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FromJSONPB Int32 Source # 
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FromJSONPB Int64 Source # 
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FromJSONPB Word32 Source # 
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Defined in Data.ProtoLens.JSONPB.Class

FromJSONPB Word64 Source # 
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Defined in Data.ProtoLens.JSONPB.Class

FromJSONPB ByteString Source # 
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FromJSONPB Text Source # 
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Defined in Data.ProtoLens.JSONPB.Class

FromJSONPB Text Source # 
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Defined in Data.ProtoLens.JSONPB.Class

FromJSONPB a => FromJSONPB [a] Source # 
Instance details

Defined in Data.ProtoLens.JSONPB.Class

Methods

parseJSONPB :: Value -> Parser [a] Source #

FromJSONPB a => FromJSONPB (Maybe a) Source # 
Instance details

Defined in Data.ProtoLens.JSONPB.Class

FromJSONPB a => FromJSONPB (Vector a) Source # 
Instance details

Defined in Data.ProtoLens.JSONPB.Class

class ToJSONPB a where Source #

ToJSON variant for JSONPB direct encoding via Encoding

Minimal complete definition

toJSONPB

Methods

toJSONPB :: a -> Options -> Value Source #

toJSON variant for JSONPB encoders.

toEncodingPB :: a -> Options -> Encoding Source #

toEncoding variant for JSONPB encoders. If an implementation is not provided, uses toJSONPB (which is less efficient since it indirects through the Value IR).

Instances
ToJSONPB Bool Source # 
Instance details

Defined in Data.ProtoLens.JSONPB.Class

ToJSONPB Double Source # 
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Defined in Data.ProtoLens.JSONPB.Class

ToJSONPB Float Source # 
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Defined in Data.ProtoLens.JSONPB.Class

ToJSONPB Int32 Source # 
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ToJSONPB Int64 Source # 
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ToJSONPB Word32 Source # 
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Defined in Data.ProtoLens.JSONPB.Class

ToJSONPB Word64 Source # 
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ToJSONPB ByteString Source # 
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Defined in Data.ProtoLens.JSONPB.Class

ToJSONPB Text Source # 
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ToJSONPB Text Source # 
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Defined in Data.ProtoLens.JSONPB.Class

ToJSONPB a => ToJSONPB [a] Source # 
Instance details

Defined in Data.ProtoLens.JSONPB.Class

Methods

toJSONPB :: [a] -> Options -> Value Source #

toEncodingPB :: [a] -> Options -> Encoding Source #

ToJSONPB a => ToJSONPB (Maybe a) Source # 
Instance details

Defined in Data.ProtoLens.JSONPB.Class

ToJSONPB a => ToJSONPB (Vector a) Source # 
Instance details

Defined in Data.ProtoLens.JSONPB.Class

Operators

(.:) :: (FromJSONPB a, FieldDefault a) => Object -> Text -> Parser a Source #

.: variant for JSONPB; if the given key is missing from the object, or if it is present but its value is null, we produce the default protobuf value for the field type

(.=) :: (ToJSONPB v, KeyValuePB kvp, FieldDefault v, Eq v) => Text -> v -> Options -> kvp Source #

Construct a monoidal key-value pair, using mempty to represent omission of default values (unless the given Options force their emission).

Options for controlling codec behavior (e.g., emitting default-valued

data Options Source #

Constructors

Options 
Instances
Show Options Source # 
Instance details

Defined in Data.ProtoLens.JSONPB.Class

defaultOptions :: Options Source #

Default options for JSONPB encoding. By default, all options are False.

JSONPB codec entry points

eitherDecode :: FromJSONPB a => ByteString -> Either String a Source #

eitherDecode variant for deserializing a JSONPB value from a lazy ByteString.

encode :: ToJSONPB a => Options -> a -> ByteString Source #

encode variant for serializing a JSONPB value as a lazy ByteString.

Helper functions

pair :: (KeyValuePB m, ToJSONPB v) => Text -> v -> Options -> m Source #

toAesonEncoding :: ToJSONPB a => a -> Encoding Source #

A direct Encoding for values which can be JSONPB-encoded

toAesonValue :: ToJSONPB a => a -> Value Source #

A Aeson Value encoder for values which can be JSONPB-encoded

Aeson re-exports

data Value #

A JSON value represented as a Haskell value.

Instances
Eq Value 
Instance details

Defined in Data.Aeson.Types.Internal

Methods

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

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

Data Value 
Instance details

Defined in Data.Aeson.Types.Internal

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 
Instance details

Defined in Data.Aeson.Types.Internal

Show Value 
Instance details

Defined in Data.Aeson.Types.Internal

Methods

showsPrec :: Int -> Value -> ShowS #

show :: Value -> String #

showList :: [Value] -> ShowS #

IsString Value 
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Defined in Data.Aeson.Types.Internal

Methods

fromString :: String -> Value #

Generic Value 
Instance details

Defined in Data.Aeson.Types.Internal

Associated Types

type Rep Value :: Type -> Type #

Methods

from :: Value -> Rep Value x #

to :: Rep Value x -> Value #

Lift Value 
Instance details

Defined in Data.Aeson.Types.Internal

Methods

lift :: Value -> Q Exp #

Hashable Value 
Instance details

Defined in Data.Aeson.Types.Internal

Methods

hashWithSalt :: Int -> Value -> Int #

hash :: Value -> Int #

ToJSON Value 
Instance details

Defined in Data.Aeson.Types.ToJSON

KeyValue Object

Constructs a singleton HashMap. For calling functions that demand an Object for constructing objects. To be used in conjunction with mconcat. Prefer to use object where possible.

Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

(.=) :: ToJSON v => Text -> v -> Object #

KeyValue Pair 
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Defined in Data.Aeson.Types.ToJSON

Methods

(.=) :: ToJSON v => Text -> v -> Pair #

FromJSON Value 
Instance details

Defined in Data.Aeson.Types.FromJSON

NFData Value 
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Defined in Data.Aeson.Types.Internal

Methods

rnf :: Value -> () #

FromString Encoding 
Instance details

Defined in Data.Aeson.Types.ToJSON

FromString Value 
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Defined in Data.Aeson.Types.ToJSON

Methods

fromString :: String -> Value

GToJSON Encoding arity (U1 :: Type -> Type) 
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Defined in Data.Aeson.Types.ToJSON

Methods

gToJSON :: Options -> ToArgs Encoding arity a -> U1 a -> Encoding

GToJSON Value arity (V1 :: Type -> Type) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

gToJSON :: Options -> ToArgs Value arity a -> V1 a -> Value

GToJSON Value arity (U1 :: Type -> Type) 
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Defined in Data.Aeson.Types.ToJSON

Methods

gToJSON :: Options -> ToArgs Value arity a -> U1 a -> Value

ToJSON1 f => GToJSON Encoding One (Rec1 f) 
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Defined in Data.Aeson.Types.ToJSON

Methods

gToJSON :: Options -> ToArgs Encoding One a -> Rec1 f a -> Encoding

ToJSON1 f => GToJSON Value One (Rec1 f) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

gToJSON :: Options -> ToArgs Value One a -> Rec1 f a -> Value

ToJSON a => GToJSON Encoding arity (K1 i a :: Type -> Type) 
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Defined in Data.Aeson.Types.ToJSON

Methods

gToJSON :: Options -> ToArgs Encoding arity a0 -> K1 i a a0 -> Encoding

(EncodeProduct arity a, EncodeProduct arity b) => GToJSON Encoding arity (a :*: b) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

gToJSON :: Options -> ToArgs Encoding arity a0 -> (a :*: b) a0 -> Encoding

ToJSON a => GToJSON Value arity (K1 i a :: Type -> Type) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

gToJSON :: Options -> ToArgs Value arity a0 -> K1 i a a0 -> Value

(WriteProduct arity a, WriteProduct arity b, ProductSize a, ProductSize b) => GToJSON Value arity (a :*: b) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

gToJSON :: Options -> ToArgs Value arity a0 -> (a :*: b) a0 -> Value

(ToJSON1 f, GToJSON Encoding One g) => GToJSON Encoding One (f :.: g) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

gToJSON :: Options -> ToArgs Encoding One a -> (f :.: g) a -> Encoding

(ToJSON1 f, GToJSON Value One g) => GToJSON Value One (f :.: g) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

gToJSON :: Options -> ToArgs Value One a -> (f :.: g) a -> Value

FromPairs Value (DList Pair) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

fromPairs :: DList Pair -> Value

v ~ Value => KeyValuePair v (DList Pair) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

pair :: String -> v -> DList Pair

KeyValuePB [Pair] Source # 
Instance details

Defined in Data.ProtoLens.JSONPB.Class

Methods

pair :: ToJSONPB v => Text -> v -> Options -> [Pair] Source #

(GToJSON Encoding arity a, ConsToJSON Encoding arity a, Constructor c) => SumToJSON' TwoElemArray Encoding arity (C1 c a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

sumToJSON' :: Options -> ToArgs Encoding arity a0 -> C1 c a a0 -> Tagged TwoElemArray Encoding

(GToJSON Value arity a, ConsToJSON Value arity a, Constructor c) => SumToJSON' TwoElemArray Value arity (C1 c a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

sumToJSON' :: Options -> ToArgs Value arity a0 -> C1 c a a0 -> Tagged TwoElemArray Value

type Rep Value 
Instance details

Defined in Data.Aeson.Types.Internal

class ToJSON a where #

A type that can be converted to JSON.

Instances in general must specify toJSON and should (but don't need to) specify toEncoding.

An example type and instance:

-- Allow ourselves to write Text literals.
{-# LANGUAGE OverloadedStrings #-}

data Coord = Coord { x :: Double, y :: Double }

instance ToJSON Coord where
  toJSON (Coord x y) = object ["x" .= x, "y" .= y]

  toEncoding (Coord x y) = pairs ("x" .= x <> "y" .= y)

Instead of manually writing your ToJSON instance, there are two options to do it automatically:

  • Data.Aeson.TH provides Template Haskell functions which will derive an instance at compile time. The generated instance is optimized for your type so it will probably be more efficient than the following option.
  • The compiler can provide a default generic implementation for toJSON.

To use the second, simply add a deriving Generic clause to your datatype and declare a ToJSON instance. If you require nothing other than defaultOptions, it is sufficient to write (and this is the only alternative where the default toJSON implementation is sufficient):

{-# LANGUAGE DeriveGeneric #-}

import GHC.Generics

data Coord = Coord { x :: Double, y :: Double } deriving Generic

instance ToJSON Coord where
    toEncoding = genericToEncoding defaultOptions

If on the other hand you wish to customize the generic decoding, you have to implement both methods:

customOptions = defaultOptions
                { fieldLabelModifier = map toUpper
                }

instance ToJSON Coord where
    toJSON     = genericToJSON customOptions
    toEncoding = genericToEncoding customOptions

Previous versions of this library only had the toJSON method. Adding toEncoding had two reasons:

  1. toEncoding is more efficient for the common case that the output of toJSON is directly serialized to a ByteString. Further, expressing either method in terms of the other would be non-optimal.
  2. The choice of defaults allows a smooth transition for existing users: Existing instances that do not define toEncoding still compile and have the correct semantics. This is ensured by making the default implementation of toEncoding use toJSON. This produces correct results, but since it performs an intermediate conversion to a Value, it will be less efficient than directly emitting an Encoding. (this also means that specifying nothing more than instance ToJSON Coord would be sufficient as a generically decoding instance, but there probably exists no good reason to not specify toEncoding in new instances.)

Minimal complete definition

Nothing

Methods

toJSON :: a -> Value #

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

toEncoding :: a -> Encoding #

Encode a Haskell value as JSON.

The default implementation of this method creates an intermediate Value using toJSON. This provides source-level compatibility for people upgrading from older versions of this library, but obviously offers no performance advantage.

To benefit from direct encoding, you must provide an implementation for this method. The easiest way to do so is by having your types implement Generic using the DeriveGeneric extension, and then have GHC generate a method body as follows.

instance ToJSON Coord where
    toEncoding = genericToEncoding defaultOptions

toJSONList :: [a] -> Value #

toEncodingList :: [a] -> Encoding #

Instances
ToJSON Bool 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON Char 
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Defined in Data.Aeson.Types.ToJSON

ToJSON Double 
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ToJSON Float 
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ToJSON Int 
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ToJSON Int8 
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ToJSON Int16 
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ToJSON Int32 
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ToJSON Int64 
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ToJSON Integer 
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Defined in Data.Aeson.Types.ToJSON

ToJSON Natural 
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Defined in Data.Aeson.Types.ToJSON

ToJSON Ordering 
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Defined in Data.Aeson.Types.ToJSON

ToJSON Word 
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ToJSON Word8 
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ToJSON Word16 
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ToJSON Word32 
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ToJSON Word64 
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Defined in Data.Aeson.Types.ToJSON

ToJSON () 
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Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: () -> Value #

toEncoding :: () -> Encoding #

toJSONList :: [()] -> Value #

toEncodingList :: [()] -> Encoding #

ToJSON Scientific 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON Text 
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Defined in Data.Aeson.Types.ToJSON

ToJSON UTCTime 
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Defined in Data.Aeson.Types.ToJSON

ToJSON Value 
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Defined in Data.Aeson.Types.ToJSON

ToJSON DotNetTime 
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ToJSON Text 
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Defined in Data.Aeson.Types.ToJSON

ToJSON Number 
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Defined in Data.Aeson.Types.ToJSON

ToJSON Void 
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ToJSON Version 
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Defined in Data.Aeson.Types.ToJSON

ToJSON CTime 
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Defined in Data.Aeson.Types.ToJSON

ToJSON IntSet 
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Defined in Data.Aeson.Types.ToJSON

ToJSON ZonedTime 
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Defined in Data.Aeson.Types.ToJSON

ToJSON LocalTime 
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Defined in Data.Aeson.Types.ToJSON

ToJSON TimeOfDay 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON SystemTime

Encoded as number

Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON NominalDiffTime 
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Defined in Data.Aeson.Types.ToJSON

ToJSON DiffTime 
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Defined in Data.Aeson.Types.ToJSON

ToJSON Day 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON CalendarDiffTime 
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Defined in Data.Aeson.Types.ToJSON

ToJSON CalendarDiffDays 
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Defined in Data.Aeson.Types.ToJSON

ToJSON DayOfWeek 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON UUID 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON [a] 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: [a] -> Value #

toEncoding :: [a] -> Encoding #

toJSONList :: [[a]] -> Value #

toEncodingList :: [[a]] -> Encoding #

ToJSON a => ToJSON (Maybe a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

(ToJSON a, Integral a) => ToJSON (Ratio a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

HasResolution a => ToJSON (Fixed a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (Min a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Min a -> Value #

toEncoding :: Min a -> Encoding #

toJSONList :: [Min a] -> Value #

toEncodingList :: [Min a] -> Encoding #

ToJSON a => ToJSON (Max a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Max a -> Value #

toEncoding :: Max a -> Encoding #

toJSONList :: [Max a] -> Value #

toEncodingList :: [Max a] -> Encoding #

ToJSON a => ToJSON (First a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (Last a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (WrappedMonoid a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (Option a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (Identity a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (First a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (Last a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (Dual a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (NonEmpty a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (IntMap a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON v => ToJSON (Tree v) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (Seq a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Seq a -> Value #

toEncoding :: Seq a -> Encoding #

toJSONList :: [Seq a] -> Value #

toEncodingList :: [Seq a] -> Encoding #

ToJSON a => ToJSON (Set a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Set a -> Value #

toEncoding :: Set a -> Encoding #

toJSONList :: [Set a] -> Value #

toEncodingList :: [Set a] -> Encoding #

ToJSON a => ToJSON (DList a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

(Prim a, ToJSON a) => ToJSON (PrimArray a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (SmallArray a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (Array a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (HashSet a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

(Vector Vector a, ToJSON a) => ToJSON (Vector a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

(Storable a, ToJSON a) => ToJSON (Vector a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

(Prim a, ToJSON a) => ToJSON (Vector a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

ToJSON a => ToJSON (Vector a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

(ToJSON a, ToJSON b) => ToJSON (Either a b) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Either a b -> Value #

toEncoding :: Either a b -> Encoding #

toJSONList :: [Either a b] -> Value #

toEncodingList :: [Either a b] -> Encoding #

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

Defined in Data.Aeson.Types.ToJSON

Methods

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

toEncoding :: (a, b) -> Encoding #

toJSONList :: [(a, b)] -> Value #

toEncodingList :: [(a, b)] -> Encoding #

(ToJSON v, ToJSONKey k) => ToJSON (HashMap k v) 
Instance details

Defined in Data.Aeson.Types.ToJSON

(ToJSON v, ToJSONKey k) => ToJSON (Map k v) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Map k v -> Value #

toEncoding :: Map k v -> Encoding #

toJSONList :: [Map k v] -> Value #

toEncodingList :: [Map k v] -> Encoding #

ToJSON (Proxy a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

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

Defined in Data.Aeson.Types.ToJSON

Methods

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

toEncoding :: (a, b, c) -> Encoding #

toJSONList :: [(a, b, c)] -> Value #

toEncodingList :: [(a, b, c)] -> Encoding #

ToJSON a => ToJSON (Const a b) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Const a b -> Value #

toEncoding :: Const a b -> Encoding #

toJSONList :: [Const a b] -> Value #

toEncodingList :: [Const a b] -> Encoding #

ToJSON b => ToJSON (Tagged a b) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Tagged a b -> Value #

toEncoding :: Tagged a b -> Encoding #

toJSONList :: [Tagged a b] -> Value #

toEncodingList :: [Tagged a b] -> Encoding #

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

Defined in Data.Aeson.Types.ToJSON

Methods

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

toEncoding :: (a, b, c, d) -> Encoding #

toJSONList :: [(a, b, c, d)] -> Value #

toEncodingList :: [(a, b, c, d)] -> Encoding #

(ToJSON1 f, ToJSON1 g, ToJSON a) => ToJSON (Product f g a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Product f g a -> Value #

toEncoding :: Product f g a -> Encoding #

toJSONList :: [Product f g a] -> Value #

toEncodingList :: [Product f g a] -> Encoding #

(ToJSON1 f, ToJSON1 g, ToJSON a) => ToJSON (Sum f g a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Sum f g a -> Value #

toEncoding :: Sum f g a -> Encoding #

toJSONList :: [Sum f g a] -> Value #

toEncodingList :: [Sum f g a] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e) => ToJSON (a, b, c, d, e) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

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

toEncoding :: (a, b, c, d, e) -> Encoding #

toJSONList :: [(a, b, c, d, e)] -> Value #

toEncodingList :: [(a, b, c, d, e)] -> Encoding #

(ToJSON1 f, ToJSON1 g, ToJSON a) => ToJSON (Compose f g a) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Compose f g a -> Value #

toEncoding :: Compose f g a -> Encoding #

toJSONList :: [Compose f g a] -> Value #

toEncodingList :: [Compose f g a] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f) => ToJSON (a, b, c, d, e, f) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

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

toEncoding :: (a, b, c, d, e, f) -> Encoding #

toJSONList :: [(a, b, c, d, e, f)] -> Value #

toEncodingList :: [(a, b, c, d, e, f)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g) => ToJSON (a, b, c, d, e, f, g) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: (a, b, c, d, e, f, g) -> Value #

toEncoding :: (a, b, c, d, e, f, g) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h) => ToJSON (a, b, c, d, e, f, g, h) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: (a, b, c, d, e, f, g, h) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i) => ToJSON (a, b, c, d, e, f, g, h, i) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: (a, b, c, d, e, f, g, h, i) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j) => ToJSON (a, b, c, d, e, f, g, h, i, j) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: (a, b, c, d, e, f, g, h, i, j) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i, j) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i, j)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i, j)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k) => ToJSON (a, b, c, d, e, f, g, h, i, j, k) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: (a, b, c, d, e, f, g, h, i, j, k) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i, j, k) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i, j, k)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i, j, k)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k, ToJSON l) => ToJSON (a, b, c, d, e, f, g, h, i, j, k, l) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: (a, b, c, d, e, f, g, h, i, j, k, l) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i, j, k, l) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i, j, k, l)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i, j, k, l)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k, ToJSON l, ToJSON m) => ToJSON (a, b, c, d, e, f, g, h, i, j, k, l, m) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k, ToJSON l, ToJSON m, ToJSON n) => ToJSON (a, b, c, d, e, f, g, h, i, j, k, l, m, n) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m, n)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m, n)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k, ToJSON l, ToJSON m, ToJSON n, ToJSON o) => ToJSON (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) 
Instance details

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)] -> Encoding #

class FromJSON a where #

A type that can be converted from JSON, with the possibility of failure.

In many cases, you can get the compiler to generate parsing code for you (see below). To begin, let's cover writing an instance by hand.

There are various reasons a conversion could fail. For example, an Object could be missing a required key, an Array could be of the wrong size, or a value could be of an incompatible type.

The basic ways to signal a failed conversion are as follows:

  • fail yields a custom error message: it is the recommended way of reporting a failure;
  • empty (or mzero) is uninformative: use it when the error is meant to be caught by some (<|>);
  • typeMismatch can be used to report a failure when the encountered value is not of the expected JSON type; unexpected is an appropriate alternative when more than one type may be expected, or to keep the expected type implicit.

prependFailure (or modifyFailure) add more information to a parser's error messages.

An example type and instance using typeMismatch and prependFailure:

-- Allow ourselves to write Text literals.
{-# LANGUAGE OverloadedStrings #-}

data Coord = Coord { x :: Double, y :: Double }

instance FromJSON Coord where
    parseJSON (Object v) = Coord
        <$> v .: "x"
        <*> v .: "y"

    -- We do not expect a non-Object value here.
    -- We could use empty to fail, but typeMismatch
    -- gives a much more informative error message.
    parseJSON invalid    =
        prependFailure "parsing Coord failed, "
            (typeMismatch "Object" invalid)

For this common case of only being concerned with a single type of JSON value, the functions withObject, withScientific, etc. are provided. Their use is to be preferred when possible, since they are more terse. Using withObject, we can rewrite the above instance (assuming the same language extension and data type) as:

instance FromJSON Coord where
    parseJSON = withObject "Coord" $ \v -> Coord
        <$> v .: "x"
        <*> v .: "y"

Instead of manually writing your FromJSON instance, there are two options to do it automatically:

  • Data.Aeson.TH provides Template Haskell functions which will derive an instance at compile time. The generated instance is optimized for your type so it will probably be more efficient than the following option.
  • The compiler can provide a default generic implementation for parseJSON.

To use the second, simply add a deriving Generic clause to your datatype and declare a FromJSON instance for your datatype without giving a definition for parseJSON.

For example, the previous example can be simplified to just:

{-# LANGUAGE DeriveGeneric #-}

import GHC.Generics

data Coord = Coord { x :: Double, y :: Double } deriving Generic

instance FromJSON Coord

The default implementation will be equivalent to parseJSON = genericParseJSON defaultOptions; if you need different options, you can customize the generic decoding by defining:

customOptions = defaultOptions
                { fieldLabelModifier = map toUpper
                }

instance FromJSON Coord where
    parseJSON = genericParseJSON customOptions

Minimal complete definition

Nothing

Methods

parseJSON :: Value -> Parser a #

parseJSONList :: Value -> Parser [a] #

Instances
FromJSON Bool 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Char 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Double 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Float 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Int 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Int8 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Int16 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Int32 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Int64 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Integer

This instance includes a bounds check to prevent maliciously large inputs to fill up the memory of the target system. You can newtype Scientific and provide your own instance using withScientific if you want to allow larger inputs.

Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Natural 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Ordering 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Word 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Word8 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Word16 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Word32 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Word64 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON () 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser () #

parseJSONList :: Value -> Parser [()] #

FromJSON Scientific 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Text 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON UTCTime 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Value 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON DotNetTime 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Text 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Void 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Version 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON CTime 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON IntSet 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON ZonedTime

Supported string formats:

YYYY-MM-DD HH:MM Z YYYY-MM-DD HH:MM:SS Z YYYY-MM-DD HH:MM:SS.SSS Z

The first space may instead be a T, and the second space is optional. The Z represents UTC. The Z may be replaced with a time zone offset of the form +0000 or -08:00, where the first two digits are hours, the : is optional and the second two digits (also optional) are minutes.

Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON LocalTime 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON TimeOfDay 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON SystemTime 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON NominalDiffTime

This instance includes a bounds check to prevent maliciously large inputs to fill up the memory of the target system. You can newtype Scientific and provide your own instance using withScientific if you want to allow larger inputs.

Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON DiffTime

This instance includes a bounds check to prevent maliciously large inputs to fill up the memory of the target system. You can newtype Scientific and provide your own instance using withScientific if you want to allow larger inputs.

Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON Day 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON CalendarDiffTime 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON CalendarDiffDays 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON DayOfWeek 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON UUID 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON [a] 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser [a] #

parseJSONList :: Value -> Parser [[a]] #

FromJSON a => FromJSON (Maybe a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

(FromJSON a, Integral a) => FromJSON (Ratio a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

HasResolution a => FromJSON (Fixed a)

This instance includes a bounds check to prevent maliciously large inputs to fill up the memory of the target system. You can newtype Scientific and provide your own instance using withScientific if you want to allow larger inputs.

Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (Min a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Min a) #

parseJSONList :: Value -> Parser [Min a] #

FromJSON a => FromJSON (Max a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Max a) #

parseJSONList :: Value -> Parser [Max a] #

FromJSON a => FromJSON (First a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (Last a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (WrappedMonoid a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (Option a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (Identity a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (First a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (Last a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (Dual a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (NonEmpty a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (IntMap a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON v => FromJSON (Tree v) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (Seq a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Seq a) #

parseJSONList :: Value -> Parser [Seq a] #

(Ord a, FromJSON a) => FromJSON (Set a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Set a) #

parseJSONList :: Value -> Parser [Set a] #

FromJSON a => FromJSON (DList a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

(Prim a, FromJSON a) => FromJSON (PrimArray a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (SmallArray a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (Array a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

(Eq a, Hashable a, FromJSON a) => FromJSON (HashSet a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

(Vector Vector a, FromJSON a) => FromJSON (Vector a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

(Storable a, FromJSON a) => FromJSON (Vector a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

(Prim a, FromJSON a) => FromJSON (Vector a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

FromJSON a => FromJSON (Vector a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

(FromJSON a, FromJSON b) => FromJSON (Either a b) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Either a b) #

parseJSONList :: Value -> Parser [Either a b] #

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

Defined in Data.Aeson.Types.FromJSON

Methods

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

parseJSONList :: Value -> Parser [(a, b)] #

(FromJSON v, FromJSONKey k, Eq k, Hashable k) => FromJSON (HashMap k v) 
Instance details

Defined in Data.Aeson.Types.FromJSON

(FromJSONKey k, Ord k, FromJSON v) => FromJSON (Map k v) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Map k v) #

parseJSONList :: Value -> Parser [Map k v] #

FromJSON (Proxy a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

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

Defined in Data.Aeson.Types.FromJSON

Methods

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

parseJSONList :: Value -> Parser [(a, b, c)] #

FromJSON a => FromJSON (Const a b) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Const a b) #

parseJSONList :: Value -> Parser [Const a b] #

FromJSON b => FromJSON (Tagged a b) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Tagged a b) #

parseJSONList :: Value -> Parser [Tagged a b] #

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

Defined in Data.Aeson.Types.FromJSON

Methods

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

parseJSONList :: Value -> Parser [(a, b, c, d)] #

(FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Product f g a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Product f g a) #

parseJSONList :: Value -> Parser [Product f g a] #

(FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Sum f g a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Sum f g a) #

parseJSONList :: Value -> Parser [Sum f g a] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e) => FromJSON (a, b, c, d, e) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

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

parseJSONList :: Value -> Parser [(a, b, c, d, e)] #

(FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Compose f g a) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Compose f g a) #

parseJSONList :: Value -> Parser [Compose f g a] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f) => FromJSON (a, b, c, d, e, f) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

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

parseJSONList :: Value -> Parser [(a, b, c, d, e, f)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g) => FromJSON (a, b, c, d, e, f, g) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h) => FromJSON (a, b, c, d, e, f, g, h) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i) => FromJSON (a, b, c, d, e, f, g, h, i) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j) => FromJSON (a, b, c, d, e, f, g, h, i, j) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i, j) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i, j)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k) => FromJSON (a, b, c, d, e, f, g, h, i, j, k) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i, j, k) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i, j, k)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k, FromJSON l) => FromJSON (a, b, c, d, e, f, g, h, i, j, k, l) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i, j, k, l) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i, j, k, l)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k, FromJSON l, FromJSON m) => FromJSON (a, b, c, d, e, f, g, h, i, j, k, l, m) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i, j, k, l, m) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i, j, k, l, m)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k, FromJSON l, FromJSON m, FromJSON n) => FromJSON (a, b, c, d, e, f, g, h, i, j, k, l, m, n) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i, j, k, l, m, n) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i, j, k, l, m, n)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k, FromJSON l, FromJSON m, FromJSON n, FromJSON o) => FromJSON (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) 
Instance details

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)] #

typeMismatch #

Arguments

:: String

The name of the JSON type being parsed ("Object", "Array", "String", "Number", "Boolean", or "Null").

-> Value

The actual value encountered.

-> Parser a 

Fail parsing due to a type mismatch, with a descriptive message.

The following wrappers should generally be prefered: withObject, withArray, withText, withBool.

Error message example

typeMismatch "Object" (String "oops")
-- Error: "expected Object, but encountered String"

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

withObject name f value applies f to the Object when value is an Object and fails otherwise.

Error message example

withObject "MyType" f (String "oops")
-- Error: "parsing MyType failed, expected Object, but encountered String"