Data.Yaml

Provides a high-level interface for processing YAML files.

This module reuses most of the infrastructure from the aeson package. This means that you can use all of the existing tools for JSON processing for processing YAML files. As a result, much of the documentation below mentions JSON; do not let that confuse you, it's intentional.

For the most part, YAML content translates directly into JSON, and therefore there is very little data loss. If you need to deal with YAML more directly (e.g., directly deal with aliases), you should use the Text.Libyaml module instead.

For documentation on the aeson types, functions, classes, and operators, please see the Data.Aeson module of the aeson package.

Look in the examples directory of the source repository for some initial pointers on how to use this library.

Encoding

encode :: ToJSON a => a -> ByteString

Encode a value into its YAML representation.

encodeWith :: ToJSON a => EncodeOptions -> a -> ByteString

Encode a value into its YAML representation with custom styling.

Since: yaml-0.10.2.0

encodeFile :: ToJSON a => FilePath -> a -> IO ()

Encode a value into its YAML representation and save to the given file.

encodeFileWith :: ToJSON a => EncodeOptions -> FilePath -> a -> IO ()

Encode a value into its YAML representation with custom styling and save to the given file.

Since: yaml-0.10.2.0

Decoding

decodeEither' :: FromJSON a => ByteString -> Either ParseException a

More helpful version of decodeEither which returns the YamlException.

Since: yaml-0.8.3

decodeFileEither :: FromJSON a => FilePath -> IO (Either ParseException a)

A version of decodeFile which should not throw runtime exceptions.

Since: yaml-0.8.4

decodeFileWithWarnings :: FromJSON a => FilePath -> IO (Either ParseException ([Warning], a))

A version of decodeFileEither that returns warnings along with the parse result.

Since: yaml-0.10.0

decodeThrow :: (MonadThrow m, FromJSON a) => ByteString -> m a

A version of decodeEither' lifted to MonadThrow

Since: yaml-0.8.31

decodeFileThrow :: (MonadIO m, FromJSON a) => FilePath -> m a

A version of decodeFileEither lifted to MonadIO

Since: yaml-0.8.31

More control over decoding

decodeHelper :: FromJSON a => ConduitM () Event Parse () -> IO (Either ParseException ([Warning], Either String a))

Types

data Value

A JSON value represented as a Haskell value.

Constructors

Object !Object

Array !Array

String !Text

Number !Scientific

Bool !Bool

Null

Instances

Eq Value

Defined in Data.Aeson.Types.Internal

Methods

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

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

Data Value

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

Defined in Data.Aeson.Types.Internal

Methods

readsPrec :: Int -> ReadS Value

readList :: ReadS [Value]

readPrec :: ReadPrec Value

readListPrec :: ReadPrec [Value]

Show Value

Defined in Data.Aeson.Types.Internal

Methods

showsPrec :: Int -> Value -> ShowS

show :: Value -> String

showList :: [Value] -> ShowS

IsString Value

Defined in Data.Aeson.Types.Internal

Methods

fromString :: String -> Value

Generic Value

Defined in Data.Aeson.Types.Internal

Associated Types

type Rep Value :: * -> *

Methods

from :: Value -> Rep Value x

to :: Rep Value x -> Value

Lift Value

Defined in Data.Aeson.Types.Internal

Methods

lift :: Value -> Q Exp

Hashable Value

Defined in Data.Aeson.Types.Internal

Methods

hashWithSalt :: Int -> Value -> Int

hash :: Value -> Int

ToJSON Value

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Value -> Value

toEncoding :: Value -> Encoding

toJSONList :: [Value] -> Value

toEncodingList :: [Value] -> Encoding

KeyValue Pair

Defined in Data.Aeson.Types.ToJSON

Methods

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

FromJSON Value

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Value

parseJSONList :: Value -> Parser [Value]

NFData Value

Defined in Data.Aeson.Types.Internal

Methods

rnf :: Value -> ()

FromString Encoding

Defined in Data.Aeson.Types.ToJSON

Methods

fromString :: String -> Encoding

FromString Value

Defined in Data.Aeson.Types.ToJSON

Methods

fromString :: String -> Value

GToJSON Encoding arity (U1 :: * -> *)

Defined in Data.Aeson.Types.ToJSON

Methods

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

GToJSON Value arity (V1 :: * -> *)

Defined in Data.Aeson.Types.ToJSON

Methods

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

GToJSON Value arity (U1 :: * -> *)

Defined in Data.Aeson.Types.ToJSON

Methods

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

ToJSON1 f => GToJSON Encoding One (Rec1 f)

Defined in Data.Aeson.Types.ToJSON

Methods

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

ToJSON1 f => GToJSON Value One (Rec1 f)

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 :: * -> *)

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)

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 :: * -> *)

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)

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)

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)

Defined in Data.Aeson.Types.ToJSON

Methods

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

FromPairs Value (DList Pair)

Defined in Data.Aeson.Types.ToJSON

Methods

fromPairs :: DList Pair -> Value

v ~ Value => KeyValuePair v (DList Pair)

Defined in Data.Aeson.Types.ToJSON

Methods

pair :: String -> v -> DList Pair

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

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)

Defined in Data.Aeson.Types.ToJSON

Methods

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

type Rep Value

Defined in Data.Aeson.Types.Internal

type Rep Value = D1 (MetaData "Value" "Data.Aeson.Types.Internal" "aeson-1.4.1.0-JaiCPnIg80cGqC9EfqkML4" False) ((C1 (MetaCons "Object" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness SourceStrict DecidedStrict) (Rec0 Object)) :+: (C1 (MetaCons "Array" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness SourceStrict DecidedStrict) (Rec0 Array)) :+: C1 (MetaCons "String" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness SourceStrict DecidedStrict) (Rec0 Text)))) :+: (C1 (MetaCons "Number" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness SourceStrict DecidedStrict) (Rec0 Scientific)) :+: (C1 (MetaCons "Bool" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness SourceStrict DecidedStrict) (Rec0 Bool)) :+: C1 (MetaCons "Null" PrefixI False) (U1 :: * -> *))))

data Parser a

A JSON parser. N.B. This might not fit your usual understanding of "parser". Instead you might like to think of Parser as a "parse result", i.e. a parser to which the input has already been applied.

Instances

Monad Parser

Defined in Data.Aeson.Types.Internal

Methods

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

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

return :: a -> Parser a

fail :: String -> Parser a

Functor Parser

Defined in Data.Aeson.Types.Internal

Methods

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

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

MonadFail Parser

Defined in Data.Aeson.Types.Internal

Methods

fail :: String -> Parser a

Applicative Parser

Defined in Data.Aeson.Types.Internal

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

Alternative Parser

Defined in Data.Aeson.Types.Internal

Methods

empty :: Parser a

(<|>) :: Parser a -> Parser a -> Parser a

some :: Parser a -> Parser [a]

many :: Parser a -> Parser [a]

MonadPlus Parser

Defined in Data.Aeson.Types.Internal

Methods

mzero :: Parser a

mplus :: Parser a -> Parser a -> Parser a

Semigroup (Parser a)

Defined in Data.Aeson.Types.Internal

Methods

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

sconcat :: NonEmpty (Parser a) -> Parser a

stimes :: Integral b => b -> Parser a -> Parser a

Monoid (Parser a)

Defined in Data.Aeson.Types.Internal

Methods

mempty :: Parser a

mappend :: Parser a -> Parser a -> Parser a

mconcat :: [Parser a] -> Parser a

type Object = HashMap Text Value

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

type Array = Vector Value

A JSON "array" (sequence).

data ParseException

Constructors

NonScalarKey

UnknownAlias

Fields

• _anchorName :: AnchorName

UnexpectedEvent

Fields

• _received :: Maybe Event
• _expected :: Maybe Event

InvalidYaml (Maybe YamlException)

AesonException String

OtherParseException SomeException

NonStringKeyAlias AnchorName Value

CyclicIncludes

Instances

Show ParseException

Defined in Data.Yaml.Internal

Methods

showsPrec :: Int -> ParseException -> ShowS

show :: ParseException -> String

showList :: [ParseException] -> ShowS

Exception ParseException

Defined in Data.Yaml.Internal

Methods

toException :: ParseException -> SomeException

fromException :: SomeException -> Maybe ParseException

displayException :: ParseException -> String

prettyPrintParseException :: ParseException -> String

Alternative to show to display a ParseException on the screen. Instead of displaying the data constructors applied to their arguments, a more textual output is returned. For example, instead of printing:

InvalidYaml (Just (YamlParseException {yamlProblem = "did not find expected ',' or '}'", yamlContext = "while parsing a flow mapping", yamlProblemMark = YamlMark {yamlIndex = 42, yamlLine = 2, yamlColumn = 12}})))

It looks more pleasant to print:

YAML parse exception at line 2, column 12,
while parsing a flow mapping:
did not find expected ',' or '}'

Since 0.8.11

data YamlException

Constructors

YamlException String

YamlParseException

problem, context, index, position line, position column

Fields

• yamlProblem :: String
• yamlContext :: String
• yamlProblemMark :: YamlMark

Instances

Show YamlException

Defined in Text.Libyaml

Methods

showsPrec :: Int -> YamlException -> ShowS

show :: YamlException -> String

showList :: [YamlException] -> ShowS

Exception YamlException

Defined in Text.Libyaml

Methods

toException :: YamlException -> SomeException

fromException :: SomeException -> Maybe YamlException

displayException :: YamlException -> String

data YamlMark

The pointer position

Constructors

YamlMark

Fields

• yamlIndex :: Int
• yamlLine :: Int
• yamlColumn :: Int

Instances

Show YamlMark

Defined in Text.Libyaml

Methods

showsPrec :: Int -> YamlMark -> ShowS

show :: YamlMark -> String

showList :: [YamlMark] -> ShowS

Constructors and accessors

object :: [Pair] -> Value

Create a Value from a list of name/value Pairs. If duplicate keys arise, earlier keys and their associated values win.

array :: [Value] -> Value

Construct a new Value from a list of Values.

(.=) :: (KeyValue kv, ToJSON v) => Text -> v -> kv infixr 8

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

Retrieve the value associated with the given key of an Object. The result is empty if the key is not present or the value cannot be converted to the desired type.

This accessor is appropriate if the key and value must be present in an object for it to be valid. If the key and value are optional, use .:? instead.

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

Retrieve the value associated with the given key of an Object. The result is Nothing if the key is not present or if its value is Null, or empty if the value cannot be converted to the desired type.

This accessor is most useful if the key and value can be absent from an object without affecting its validity. If the key and value are mandatory, use .: instead.

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

Helper for use in combination with .:? to provide default values for optional JSON object fields.

This combinator is most useful if the key and value can be absent from an object without affecting its validity and we know a default value to assign in that case. If the key and value are mandatory, use .: instead.

Example usage:

 v1 <- o .:? "opt_field_with_dfl" .!= "default_val"
 v2 <- o .:  "mandatory_field"
 v3 <- o .:? "opt_field2"

With helpers (since 0.8.23)

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

withObject expected f value applies f to the Object when value is an Object and fails using typeMismatch expected otherwise.

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

withText expected f value applies f to the Text when value is a String and fails using typeMismatch expected otherwise.

withArray :: String -> (Array -> Parser a) -> Value -> Parser a

withArray expected f value applies f to the Array when value is an Array and fails using typeMismatch expected otherwise.

withScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a

withScientific expected f value applies f to the Scientific number when value is a Number and fails using typeMismatch expected otherwise. . Warning: If you are converting from a scientific to an unbounded type such as Integer you may want to add a restriction on the size of the exponent (see withBoundedScientific) to prevent malicious input from filling up the memory of the target system.

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

withBool expected f value applies f to the Bool when value is a Bool and fails using typeMismatch expected otherwise.

Parsing

parseMonad :: Monad m => (a -> Parser b) -> a -> m b

parseEither :: (a -> Parser b) -> a -> Either String b

Run a Parser with an Either result type. If the parse fails, the Left payload will contain an error message.

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

Run a Parser with a Maybe result type.

Classes

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.)

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

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Bool -> Value

toEncoding :: Bool -> Encoding

toJSONList :: [Bool] -> Value

toEncodingList :: [Bool] -> Encoding

ToJSON Char

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Char -> Value

toEncoding :: Char -> Encoding

toJSONList :: [Char] -> Value

toEncodingList :: [Char] -> Encoding

ToJSON Double

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Double -> Value

toEncoding :: Double -> Encoding

toJSONList :: [Double] -> Value

toEncodingList :: [Double] -> Encoding

ToJSON Float

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Float -> Value

toEncoding :: Float -> Encoding

toJSONList :: [Float] -> Value

toEncodingList :: [Float] -> Encoding

ToJSON Int

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Int -> Value

toEncoding :: Int -> Encoding

toJSONList :: [Int] -> Value

toEncodingList :: [Int] -> Encoding

ToJSON Int8

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Int8 -> Value

toEncoding :: Int8 -> Encoding

toJSONList :: [Int8] -> Value

toEncodingList :: [Int8] -> Encoding

ToJSON Int16

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Int16 -> Value

toEncoding :: Int16 -> Encoding

toJSONList :: [Int16] -> Value

toEncodingList :: [Int16] -> Encoding

ToJSON Int32

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Int32 -> Value

toEncoding :: Int32 -> Encoding

toJSONList :: [Int32] -> Value

toEncodingList :: [Int32] -> Encoding

ToJSON Int64

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Int64 -> Value

toEncoding :: Int64 -> Encoding

toJSONList :: [Int64] -> Value

toEncodingList :: [Int64] -> Encoding

ToJSON Integer

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Integer -> Value

toEncoding :: Integer -> Encoding

toJSONList :: [Integer] -> Value

toEncodingList :: [Integer] -> Encoding

ToJSON Natural

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Natural -> Value

toEncoding :: Natural -> Encoding

toJSONList :: [Natural] -> Value

toEncodingList :: [Natural] -> Encoding

ToJSON Ordering

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Ordering -> Value

toEncoding :: Ordering -> Encoding

toJSONList :: [Ordering] -> Value

toEncodingList :: [Ordering] -> Encoding

ToJSON Word

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Word -> Value

toEncoding :: Word -> Encoding

toJSONList :: [Word] -> Value

toEncodingList :: [Word] -> Encoding

ToJSON Word8

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Word8 -> Value

toEncoding :: Word8 -> Encoding

toJSONList :: [Word8] -> Value

toEncodingList :: [Word8] -> Encoding

ToJSON Word16

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Word16 -> Value

toEncoding :: Word16 -> Encoding

toJSONList :: [Word16] -> Value

toEncodingList :: [Word16] -> Encoding

ToJSON Word32

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Word32 -> Value

toEncoding :: Word32 -> Encoding

toJSONList :: [Word32] -> Value

toEncodingList :: [Word32] -> Encoding

ToJSON Word64

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Word64 -> Value

toEncoding :: Word64 -> Encoding

toJSONList :: [Word64] -> Value

toEncodingList :: [Word64] -> Encoding

ToJSON ()

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: () -> Value

toEncoding :: () -> Encoding

toJSONList :: [()] -> Value

toEncodingList :: [()] -> Encoding

ToJSON Scientific

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Scientific -> Value

toEncoding :: Scientific -> Encoding

toJSONList :: [Scientific] -> Value

toEncodingList :: [Scientific] -> Encoding

ToJSON Text

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Text -> Value

toEncoding :: Text -> Encoding

toJSONList :: [Text] -> Value

toEncodingList :: [Text] -> Encoding

ToJSON UTCTime

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: UTCTime -> Value

toEncoding :: UTCTime -> Encoding

toJSONList :: [UTCTime] -> Value

toEncodingList :: [UTCTime] -> Encoding

ToJSON Value

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Value -> Value

toEncoding :: Value -> Encoding

toJSONList :: [Value] -> Value

toEncodingList :: [Value] -> Encoding

ToJSON DotNetTime

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: DotNetTime -> Value

toEncoding :: DotNetTime -> Encoding

toJSONList :: [DotNetTime] -> Value

toEncodingList :: [DotNetTime] -> Encoding

ToJSON Text

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Text -> Value

toEncoding :: Text -> Encoding

toJSONList :: [Text] -> Value

toEncodingList :: [Text] -> Encoding

ToJSON Number

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Number -> Value

toEncoding :: Number -> Encoding

toJSONList :: [Number] -> Value

toEncodingList :: [Number] -> Encoding

ToJSON Void

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Void -> Value

toEncoding :: Void -> Encoding

toJSONList :: [Void] -> Value

toEncodingList :: [Void] -> Encoding

ToJSON Version

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Version -> Value

toEncoding :: Version -> Encoding

toJSONList :: [Version] -> Value

toEncodingList :: [Version] -> Encoding

ToJSON CTime

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: CTime -> Value

toEncoding :: CTime -> Encoding

toJSONList :: [CTime] -> Value

toEncodingList :: [CTime] -> Encoding

ToJSON IntSet

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: IntSet -> Value

toEncoding :: IntSet -> Encoding

toJSONList :: [IntSet] -> Value

toEncodingList :: [IntSet] -> Encoding

ToJSON ZonedTime

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: ZonedTime -> Value

toEncoding :: ZonedTime -> Encoding

toJSONList :: [ZonedTime] -> Value

toEncodingList :: [ZonedTime] -> Encoding

ToJSON LocalTime

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: LocalTime -> Value

toEncoding :: LocalTime -> Encoding

toJSONList :: [LocalTime] -> Value

toEncodingList :: [LocalTime] -> Encoding

ToJSON TimeOfDay

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: TimeOfDay -> Value

toEncoding :: TimeOfDay -> Encoding

toJSONList :: [TimeOfDay] -> Value

toEncodingList :: [TimeOfDay] -> Encoding

ToJSON NominalDiffTime

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: NominalDiffTime -> Value

toEncoding :: NominalDiffTime -> Encoding

toJSONList :: [NominalDiffTime] -> Value

toEncodingList :: [NominalDiffTime] -> Encoding

ToJSON DiffTime

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: DiffTime -> Value

toEncoding :: DiffTime -> Encoding

toJSONList :: [DiffTime] -> Value

toEncodingList :: [DiffTime] -> Encoding

ToJSON Day

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Day -> Value

toEncoding :: Day -> Encoding

toJSONList :: [Day] -> Value

toEncodingList :: [Day] -> Encoding

ToJSON UUID

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: UUID -> Value

toEncoding :: UUID -> Encoding

toJSONList :: [UUID] -> Value

toEncodingList :: [UUID] -> Encoding

ToJSON a => ToJSON [a]

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: [a] -> Value

toEncoding :: [a] -> Encoding

toJSONList :: [[a]] -> Value

toEncodingList :: [[a]] -> Encoding

ToJSON a => ToJSON (Maybe a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Maybe a -> Value

toEncoding :: Maybe a -> Encoding

toJSONList :: [Maybe a] -> Value

toEncodingList :: [Maybe a] -> Encoding

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

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Ratio a -> Value

toEncoding :: Ratio a -> Encoding

toJSONList :: [Ratio a] -> Value

toEncodingList :: [Ratio a] -> Encoding

HasResolution a => ToJSON (Fixed a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Fixed a -> Value

toEncoding :: Fixed a -> Encoding

toJSONList :: [Fixed a] -> Value

toEncodingList :: [Fixed a] -> Encoding

ToJSON a => ToJSON (Min a)

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)

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)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: First a -> Value

toEncoding :: First a -> Encoding

toJSONList :: [First a] -> Value

toEncodingList :: [First a] -> Encoding

ToJSON a => ToJSON (Last a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Last a -> Value

toEncoding :: Last a -> Encoding

toJSONList :: [Last a] -> Value

toEncodingList :: [Last a] -> Encoding

ToJSON a => ToJSON (WrappedMonoid a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: WrappedMonoid a -> Value

toEncoding :: WrappedMonoid a -> Encoding

toJSONList :: [WrappedMonoid a] -> Value

toEncodingList :: [WrappedMonoid a] -> Encoding

ToJSON a => ToJSON (Option a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Option a -> Value

toEncoding :: Option a -> Encoding

toJSONList :: [Option a] -> Value

toEncodingList :: [Option a] -> Encoding

ToJSON a => ToJSON (Identity a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Identity a -> Value

toEncoding :: Identity a -> Encoding

toJSONList :: [Identity a] -> Value

toEncodingList :: [Identity a] -> Encoding

ToJSON a => ToJSON (First a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: First a -> Value

toEncoding :: First a -> Encoding

toJSONList :: [First a] -> Value

toEncodingList :: [First a] -> Encoding

ToJSON a => ToJSON (Last a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Last a -> Value

toEncoding :: Last a -> Encoding

toJSONList :: [Last a] -> Value

toEncodingList :: [Last a] -> Encoding

ToJSON a => ToJSON (Dual a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Dual a -> Value

toEncoding :: Dual a -> Encoding

toJSONList :: [Dual a] -> Value

toEncodingList :: [Dual a] -> Encoding

ToJSON a => ToJSON (NonEmpty a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: NonEmpty a -> Value

toEncoding :: NonEmpty a -> Encoding

toJSONList :: [NonEmpty a] -> Value

toEncodingList :: [NonEmpty a] -> Encoding

ToJSON a => ToJSON (IntMap a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: IntMap a -> Value

toEncoding :: IntMap a -> Encoding

toJSONList :: [IntMap a] -> Value

toEncodingList :: [IntMap a] -> Encoding

ToJSON v => ToJSON (Tree v)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Tree v -> Value

toEncoding :: Tree v -> Encoding

toJSONList :: [Tree v] -> Value

toEncodingList :: [Tree v] -> Encoding

ToJSON a => ToJSON (Seq a)

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)

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)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: DList a -> Value

toEncoding :: DList a -> Encoding

toJSONList :: [DList a] -> Value

toEncodingList :: [DList a] -> Encoding

(PrimUnlifted a, ToJSON a) => ToJSON (UnliftedArray a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: UnliftedArray a -> Value

toEncoding :: UnliftedArray a -> Encoding

toJSONList :: [UnliftedArray a] -> Value

toEncodingList :: [UnliftedArray a] -> Encoding

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

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: PrimArray a -> Value

toEncoding :: PrimArray a -> Encoding

toJSONList :: [PrimArray a] -> Value

toEncodingList :: [PrimArray a] -> Encoding

ToJSON a => ToJSON (SmallArray a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: SmallArray a -> Value

toEncoding :: SmallArray a -> Encoding

toJSONList :: [SmallArray a] -> Value

toEncodingList :: [SmallArray a] -> Encoding

ToJSON a => ToJSON (Array a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Array a -> Value

toEncoding :: Array a -> Encoding

toJSONList :: [Array a] -> Value

toEncodingList :: [Array a] -> Encoding

ToJSON a => ToJSON (HashSet a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: HashSet a -> Value

toEncoding :: HashSet a -> Encoding

toJSONList :: [HashSet a] -> Value

toEncodingList :: [HashSet a] -> Encoding

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

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Vector a -> Value

toEncoding :: Vector a -> Encoding

toJSONList :: [Vector a] -> Value

toEncodingList :: [Vector a] -> Encoding

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

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Vector a -> Value

toEncoding :: Vector a -> Encoding

toJSONList :: [Vector a] -> Value

toEncodingList :: [Vector a] -> Encoding

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

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Vector a -> Value

toEncoding :: Vector a -> Encoding

toJSONList :: [Vector a] -> Value

toEncodingList :: [Vector a] -> Encoding

ToJSON a => ToJSON (Vector a)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Vector a -> Value

toEncoding :: Vector a -> Encoding

toJSONList :: [Vector a] -> Value

toEncodingList :: [Vector a] -> Encoding

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

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)

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)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: HashMap k v -> Value

toEncoding :: HashMap k v -> Encoding

toJSONList :: [HashMap k v] -> Value

toEncodingList :: [HashMap k v] -> Encoding

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

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)

Defined in Data.Aeson.Types.ToJSON

Methods

toJSON :: Proxy a -> Value

toEncoding :: Proxy a -> Encoding

toJSONList :: [Proxy a] -> Value

toEncodingList :: [Proxy a] -> Encoding

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

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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:

• empty and mzero work, but are terse and uninformative;
• fail yields a custom error message;
• typeMismatch produces an informative message for cases when the value encountered is not of the expected type.

An example type and instance using typeMismatch:

-- 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 mzero to fail, but typeMismatch
    -- gives a much more informative error message.
    parseJSON invalid    = typeMismatch "Coord" invalid

For this common case of only being concerned with a single type of JSON value, the functions withObject, withNumber, 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

Methods

parseJSON :: Value -> Parser a

parseJSONList :: Value -> Parser [a]

Instances

FromJSON Bool

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Bool

parseJSONList :: Value -> Parser [Bool]

FromJSON Char

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Char

parseJSONList :: Value -> Parser [Char]

FromJSON Double

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Double

parseJSONList :: Value -> Parser [Double]

FromJSON Float

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Float

parseJSONList :: Value -> Parser [Float]

FromJSON Int

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Int

parseJSONList :: Value -> Parser [Int]

FromJSON Int8

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Int8

parseJSONList :: Value -> Parser [Int8]

FromJSON Int16

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Int16

parseJSONList :: Value -> Parser [Int16]

FromJSON Int32

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Int32

parseJSONList :: Value -> Parser [Int32]

FromJSON Int64

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Int64

parseJSONList :: Value -> Parser [Int64]

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.

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Integer

parseJSONList :: Value -> Parser [Integer]

FromJSON Natural

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Natural

parseJSONList :: Value -> Parser [Natural]

FromJSON Ordering

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Ordering

parseJSONList :: Value -> Parser [Ordering]

FromJSON Word

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Word

parseJSONList :: Value -> Parser [Word]

FromJSON Word8

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Word8

parseJSONList :: Value -> Parser [Word8]

FromJSON Word16

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Word16

parseJSONList :: Value -> Parser [Word16]

FromJSON Word32

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Word32

parseJSONList :: Value -> Parser [Word32]

FromJSON Word64

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Word64

parseJSONList :: Value -> Parser [Word64]

FromJSON ()

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser ()

parseJSONList :: Value -> Parser [()]

FromJSON Scientific

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Scientific

parseJSONList :: Value -> Parser [Scientific]

FromJSON Text

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Text

parseJSONList :: Value -> Parser [Text]

FromJSON UTCTime

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser UTCTime

parseJSONList :: Value -> Parser [UTCTime]

FromJSON Value

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Value

parseJSONList :: Value -> Parser [Value]

FromJSON DotNetTime

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser DotNetTime

parseJSONList :: Value -> Parser [DotNetTime]

FromJSON Text

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Text

parseJSONList :: Value -> Parser [Text]

FromJSON Void

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Void

parseJSONList :: Value -> Parser [Void]

FromJSON Version

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Version

parseJSONList :: Value -> Parser [Version]

FromJSON CTime

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser CTime

parseJSONList :: Value -> Parser [CTime]

FromJSON IntSet

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser IntSet

parseJSONList :: Value -> Parser [IntSet]

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.

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser ZonedTime

parseJSONList :: Value -> Parser [ZonedTime]

FromJSON LocalTime

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser LocalTime

parseJSONList :: Value -> Parser [LocalTime]

FromJSON TimeOfDay

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser TimeOfDay

parseJSONList :: Value -> Parser [TimeOfDay]

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.

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser NominalDiffTime

parseJSONList :: Value -> Parser [NominalDiffTime]

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.

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser DiffTime

parseJSONList :: Value -> Parser [DiffTime]

FromJSON Day

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser Day

parseJSONList :: Value -> Parser [Day]

FromJSON UUID

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser UUID

parseJSONList :: Value -> Parser [UUID]

FromJSON a => FromJSON [a]

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser [a]

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

FromJSON a => FromJSON (Maybe a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Maybe a)

parseJSONList :: Value -> Parser [Maybe a]

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

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Ratio a)

parseJSONList :: Value -> Parser [Ratio a]

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.

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Fixed a)

parseJSONList :: Value -> Parser [Fixed a]

FromJSON a => FromJSON (Min a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Min a)

parseJSONList :: Value -> Parser [Min a]

FromJSON a => FromJSON (Max a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Max a)

parseJSONList :: Value -> Parser [Max a]

FromJSON a => FromJSON (First a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (First a)

parseJSONList :: Value -> Parser [First a]

FromJSON a => FromJSON (Last a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Last a)

parseJSONList :: Value -> Parser [Last a]

FromJSON a => FromJSON (WrappedMonoid a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (WrappedMonoid a)

parseJSONList :: Value -> Parser [WrappedMonoid a]

FromJSON a => FromJSON (Option a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Option a)

parseJSONList :: Value -> Parser [Option a]

FromJSON a => FromJSON (Identity a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Identity a)

parseJSONList :: Value -> Parser [Identity a]

FromJSON a => FromJSON (First a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (First a)

parseJSONList :: Value -> Parser [First a]

FromJSON a => FromJSON (Last a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Last a)

parseJSONList :: Value -> Parser [Last a]

FromJSON a => FromJSON (Dual a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Dual a)

parseJSONList :: Value -> Parser [Dual a]

FromJSON a => FromJSON (NonEmpty a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (NonEmpty a)

parseJSONList :: Value -> Parser [NonEmpty a]

FromJSON a => FromJSON (IntMap a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (IntMap a)

parseJSONList :: Value -> Parser [IntMap a]

FromJSON v => FromJSON (Tree v)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Tree v)

parseJSONList :: Value -> Parser [Tree v]

FromJSON a => FromJSON (Seq a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Seq a)

parseJSONList :: Value -> Parser [Seq a]

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

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Set a)

parseJSONList :: Value -> Parser [Set a]

FromJSON a => FromJSON (DList a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (DList a)

parseJSONList :: Value -> Parser [DList a]

(PrimUnlifted a, FromJSON a) => FromJSON (UnliftedArray a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (UnliftedArray a)

parseJSONList :: Value -> Parser [UnliftedArray a]

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

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (PrimArray a)

parseJSONList :: Value -> Parser [PrimArray a]

FromJSON a => FromJSON (SmallArray a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (SmallArray a)

parseJSONList :: Value -> Parser [SmallArray a]

FromJSON a => FromJSON (Array a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Array a)

parseJSONList :: Value -> Parser [Array a]

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

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (HashSet a)

parseJSONList :: Value -> Parser [HashSet a]

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

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Vector a)

parseJSONList :: Value -> Parser [Vector a]

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

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Vector a)

parseJSONList :: Value -> Parser [Vector a]

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

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Vector a)

parseJSONList :: Value -> Parser [Vector a]

FromJSON a => FromJSON (Vector a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Vector a)

parseJSONList :: Value -> Parser [Vector a]

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

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)

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)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (HashMap k v)

parseJSONList :: Value -> Parser [HashMap k v]

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

Defined in Data.Aeson.Types.FromJSON

Methods

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

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

FromJSON (Proxy a)

Defined in Data.Aeson.Types.FromJSON

Methods

parseJSON :: Value -> Parser (Proxy a)

parseJSONList :: Value -> Parser [Proxy a]

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

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)]

Custom encoding

isSpecialString :: Text -> Bool

Determine whether a string must be quoted in YAML and can't appear as plain text. Useful if you want to use setStringStyle.

Since: yaml-0.10.2.0

data EncodeOptions

Since: yaml-0.10.2.0

defaultEncodeOptions :: EncodeOptions

Since: yaml-0.10.2.0

setStringStyle :: (Text -> (Tag, Style)) -> EncodeOptions -> EncodeOptions

Set the string style in the encoded YAML. This is a function that decides for each string the type of YAML string to output.

WARNING: You must ensure that special strings (like "yes"/"no"/"null"/"1234") are not encoded with the Plain style, because then they will be decoded as boolean, null or numeric values. You can use isSpecialString to detect them.

By default, strings are encoded as follows:

• Any string containing a newline character uses the Literal style
• Otherwise, any special string (see isSpecialString) uses SingleQuoted
• Otherwise, use Plain

Since: yaml-0.10.2.0

setFormat :: FormatOptions -> EncodeOptions -> EncodeOptions

Set the encoding formatting for the encoded YAML. By default, this is defaultFormatOptions.

Since: yaml-0.10.2.0

data FormatOptions

Contains options relating to the formatting (indendation, width) of the YAML output.

Since: yaml-0.10.2.0

defaultFormatOptions :: FormatOptions

Since: yaml-0.10.2.0

setWidth :: Maybe Int -> FormatOptions -> FormatOptions

Set the maximum number of columns in the YAML output, or Nothing for infinite. By default, the limit is 80 characters.

Since: yaml-0.10.2.0

Deprecated

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

Deprecated: Please use decodeEither or decodeThrow, which provide information on how the decode failed

decodeFile :: FromJSON a => FilePath -> IO (Maybe a)

Deprecated: Please use decodeFileEither, which does not confused type-directed and runtime exceptions.

decodeEither :: FromJSON a => ByteString -> Either String a

Deprecated: Please use decodeEither' or decodeThrow, which provide more useful failures