AesonDecode

Decoder

newtype Decoder a

Some way of interpreting a JSON value, with the possibility of failure for some values

Constructors

Decoder

Fields

• decodeMaybe :: Value -> Maybe a

Instances

Alternative Decoder

empty = failDecoder, <|> = orElse

Defined in AesonDecode

Methods

empty :: Decoder a

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

some :: Decoder a -> Decoder [a]

many :: Decoder a -> Decoder [a]

Applicative Decoder

pure = constSuccessDecoder, <*> = apDecoder

Defined in AesonDecode

Methods

pure :: a -> Decoder a

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

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

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

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

Functor Decoder

fmap = mapDecoder

Defined in AesonDecode

Methods

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

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

Monad Decoder

>=> = composeDecoderFunctions

Defined in AesonDecode

Methods

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

(>>) :: Decoder a -> Decoder b -> Decoder b

return :: a -> Decoder a

FromJSON a => Default (Decoder a)

def = defaultDecoder

Defined in AesonDecode

Methods

def :: Decoder a

constDecoder

Arguments

:: Maybe a

The result that the decoder always produces

-> Decoder a

A decoder that always produces the given result

Always produces the same result

constSuccessDecoder :: a -> Decoder a

Always succeeds and produces the same result

failDecoder :: Decoder a

Always fails

This is the identity of the Alternative for Decoder.

mapDecoder :: (a -> b) -> Decoder a -> Decoder b

apDecoder :: Decoder (a -> b) -> Decoder a -> Decoder b

composeDecoderFunctions :: (b -> Decoder c) -> (a -> Decoder b) -> a -> Decoder c

Compose two decoder-producing functions

orElse :: Decoder a -> Decoder a -> Decoder a

defaultDecoder :: FromJSON a => Decoder a

is :: (Eq a, FromJSON a) => a -> Decoder ()

is x produces Just () if the JSON value decodes to x, or Nothing otherwise

(^?) :: Value -> Decoder a -> Maybe a infixl 8

Path

newtype Path

Constructors

Path

Fields

• getAt :: Value -> Maybe Value

Instances

IsString Path

fromString = stringPath

Defined in AesonDecode

Methods

fromString :: String -> Path

Monoid Path

mempty = here

Defined in AesonDecode

Methods

mempty :: Path

mappend :: Path -> Path -> Path

mconcat :: [Path] -> Path

Semigroup Path

<> = pathConcat@

Defined in AesonDecode

Methods

(<>) :: Path -> Path -> Path

sconcat :: NonEmpty Path -> Path

stimes :: Integral b => b -> Path -> Path

here :: Path

The empty path

This is the identity of the Monoid for Path.

stringPath :: String -> Path

textPath :: Text -> Path

at :: Path -> Decoder a -> Decoder a

only :: Path

Selects the only element from an array of length 1

Text

text :: Decoder Text

Decodes a JSON string as Text

textIs :: Text -> Decoder ()

Just () if the JSON value is the given string, Nothing otherwise

Integer

integer :: Decoder Integer

Decodes a JSON number as an Integer

integerIs :: Integer -> Decoder ()

Just () if the JSON value is the given integer, Nothing otherwise

Boolean

bool :: Decoder Bool

Decodes a JSON boolean as a Bool

boolIs :: Bool -> Decoder ()

Just () if the JSON value is the given boolean, Nothing otherwise

true :: Decoder ()

Just () if the JSON value is true, Nothing otherwise

false :: Decoder ()

Just () if the JSON value is false, Nothing otherwise

List

listOf :: Decoder a -> Decoder [a]

Vector

vectorOf :: Decoder a -> Decoder (Vector a)

Ord map

ordMapOf :: Decoder a -> Decoder (Map Text a)

Hash map

hashMapOf :: Decoder a -> Decoder (HashMap Text a)

Null

null :: Decoder ()

Just () if the JSON value is the value null, Nothing otherwise

nullable :: Decoder a -> Decoder (Maybe a)

Succeeds with Just x if the decoder d succeeds with value x, succeeds with Nothing if the JSON value is null, fails otherwise