Elm.Aeson

Options used to derive FromJSON/ToJSON instance. These options generally comply to elm-street rules regarding names.

Documentation

elmStreetParseJson :: forall a. (Typeable a, Generic a, GFromJSON Zero (Rep a)) => Value -> Parser a

Allows to create FromJSON instance that strips the supported by elm-street data type name prefix from every field..

Example:

With the following JSON

{ "name": "John"
, "age": 42
}

it is decoded it the following way for each of the specified types:

Haskell data type	Parsed type
data User = User { userName :: String , userAge :: Int }	User { userName = "John" , userAge = 42 }
data LongUser = LongUser { luName :: String , luAge :: Int }	LongUser { luName = "John" , luAge = 42 }
data SimpleUser = SimpleUser { name :: String , age :: Int }	SimpleUser { name = "John" , age = 42 }

>>> data User = User { userName :: String, userAge :: Int } deriving (Generic, Show)
>>> instance FromJSON User where parseJSON = elmStreetParseJson
>>> decode @User "{ \"name\": \"John\", \"age\": 42 }"
Just (User {userName = "John", userAge = 42})

>>> data VeryLongType = VeryLongType { vltName :: String, vltAge :: Int } deriving (Generic, Show)
>>> instance FromJSON VeryLongType where parseJSON = elmStreetParseJson
>>> decode @VeryLongType "{ \"name\": \"John\", \"age\": 42 }"
Just (VeryLongType {vltName = "John", vltAge = 42})

elmStreetToJson :: forall a. (Typeable a, Generic a, GToJSON Zero (Rep a)) => a -> Value

Allows to create ToJSON instance that strips the supported by elm-street data type name prefix from every field.

>>> data User = User { userName :: String, userAge :: Int } deriving (Generic, Show)
>>> instance ToJSON User where toJSON = elmStreetToJson
>>> encode $ User { userName = "John", userAge = 42 }
"{\"age\":42,\"name\":\"John\"}"

>>> data VeryLongType = VeryLongType { vltName :: String, vltAge :: Int } deriving (Generic, Show)
>>> instance ToJSON VeryLongType where toJSON = elmStreetToJson
>>> encode $ VeryLongType {vltName = "John", vltAge = 42}
"{\"age\":42,\"name\":\"John\"}"

>>> data User = User { name :: String, age :: Int } deriving (Generic, Show)
>>> instance ToJSON User where toJSON = elmStreetToJson
>>> encode $ User { name = "John", age = 42 }
"{\"age\":42,\"name\":\"John\"}"

elmStreetJsonOptions :: forall a. Typeable a => Options

Options to strip type name from the field names.

Data type name	Field name	Stripped field name
User	userName	name
AaaBbbCcc	abcFieldName	fieldName
Foo	field	field
Field	field	field

newtype ElmStreet a

Newtype for reusing in DerivingVia.

In order to use it with your type MyType add the following deriving to your type:

    deriving (Elm, ToJSON, FromJSON) via ElmStreet MyType

Constructors

ElmStreet

Fields

• unElmStreet :: a

Instances

(Typeable a, Generic a, GToJSON Zero (Rep a)) => ToJSON (ElmStreet a)

Defined in Elm.Aeson

Methods

toJSON :: ElmStreet a -> Value

toEncoding :: ElmStreet a -> Encoding

toJSONList :: [ElmStreet a] -> Value

toEncodingList :: [ElmStreet a] -> Encoding

(Typeable a, Generic a, GFromJSON Zero (Rep a)) => FromJSON (ElmStreet a)

Defined in Elm.Aeson

Methods

parseJSON :: Value -> Parser (ElmStreet a)

parseJSONList :: Value -> Parser [ElmStreet a]

(HasNoTypeVars a, HasLessThanEightUnnamedFields a, HasNoNamedSum a, Generic a, GenericElmDefinition (Rep a)) => Elm (ElmStreet a)

Defined in Elm.Aeson

Methods

toElmDefinition :: Proxy (ElmStreet a) -> ElmDefinition