Generics.Generic.Aeson

This module offers generic conversions to and from JSON Values for data types with a Generic instance.

The structure of the generated JSON is meant to be close to idiomatic JSON. This means:

• Enumerations are converted to JSON strings.
• Record fields become JSON keys.
• Data types with one unlabeled field convert to just that field.
• Data types with multiple unlabeled fields become arrays.
• Multiple constructors are represented by keys.
• Maybe values are either an absent key, or the value.

See 'tests/Main.hs' for more examples.

Documentation

gtoJson :: forall a. (Generic a, GtoJson (Rep a), ConNames (Rep a), GIsEnum (Rep a)) => a -> Value

Convert any datatype with a Generic instance to a JSON Value.

gparseJson :: forall a. (Generic a, GfromJson (Rep a), ConNames (Rep a), GIsEnum (Rep a)) => Value -> Parser a

Parse any datatype with a Generic instance from a JSON Value.

class GtoJson f where

Class for converting the functors from GHC.Generics to JSON. You generally don't need to give any custom instances. Just add 'deriving Generic' and call gToJson.

Methods

gtoJSONf :: Settings -> Bool -> Bool -> f a -> Either [Value] [(Text, Value)]

Generically show a functor as a JSON value. The first argument tells us if there are multiple constructors in the data type. The second indicates if this data type is an enumeration (only empty constructors). A functor is then converted to either a list of values (for non-labeled fields) or a list of String/value pairs (for labeled fields).

Instances

GtoJson (U1 :: Type -> Type)

Defined in Generics.Generic.Aeson

Methods

gtoJSONf :: Settings -> Bool -> Bool -> U1 a -> Either [Value] [(Text, Value)]

ToJSON c => GtoJson (K1 a c :: Type -> Type)

Defined in Generics.Generic.Aeson

Methods

gtoJSONf :: Settings -> Bool -> Bool -> K1 a c a0 -> Either [Value] [(Text, Value)]

(GtoJson f, GtoJson g) => GtoJson (f :+: g)

Defined in Generics.Generic.Aeson

Methods

gtoJSONf :: Settings -> Bool -> Bool -> (f :+: g) a -> Either [Value] [(Text, Value)]

(GtoJson f, GtoJson g) => GtoJson (f :*: g)

Defined in Generics.Generic.Aeson

Methods

gtoJSONf :: Settings -> Bool -> Bool -> (f :*: g) a -> Either [Value] [(Text, Value)]

GtoJson f => GtoJson (M1 D c f)

Defined in Generics.Generic.Aeson

Methods

gtoJSONf :: Settings -> Bool -> Bool -> M1 D c f a -> Either [Value] [(Text, Value)]

(Constructor c, GtoJson f) => GtoJson (M1 C c f)

Defined in Generics.Generic.Aeson

Methods

gtoJSONf :: Settings -> Bool -> Bool -> M1 C c f a -> Either [Value] [(Text, Value)]

(Selector c, ToJSON a) => GtoJson (M1 S c (K1 i (Maybe a) :: Type -> Type))

Defined in Generics.Generic.Aeson

Methods

gtoJSONf :: Settings -> Bool -> Bool -> M1 S c (K1 i (Maybe a)) a0 -> Either [Value] [(Text, Value)]

(Selector c, GtoJson f) => GtoJson (M1 S c f)

Defined in Generics.Generic.Aeson

Methods

gtoJSONf :: Settings -> Bool -> Bool -> M1 S c f a -> Either [Value] [(Text, Value)]

class GfromJson f where

Class for parsing the functors from GHC.Generics from JSON. You generally don't need to give any custom instances. Just add 'deriving Generic' and call gFromJson.

Methods

gparseJSONf :: Settings -> Bool -> Bool -> Bool -> StateT [Value] Parser (f a)

Generically read a functor from a JSON value. The first argument tells us if there are multiple constructors in the data type. The second indicates if we've already detected that this data type has multiple constructors. When this is False, the (:*:) puts the fields in the state. The third indicates if this data type is an enumeration (only empty constructors). The third is a function for parsing the recursive positions. A JSON value is then parsed to either a functor, or a failure.

Instances

GfromJson (U1 :: Type -> Type)

Defined in Generics.Generic.Aeson

Methods

gparseJSONf :: Settings -> Bool -> Bool -> Bool -> StateT [Value] Parser (U1 a)

FromJSON c => GfromJson (K1 a c :: Type -> Type)

Defined in Generics.Generic.Aeson

Methods

gparseJSONf :: Settings -> Bool -> Bool -> Bool -> StateT [Value] Parser (K1 a c a0)

(GfromJson f, GfromJson g) => GfromJson (f :+: g)

Defined in Generics.Generic.Aeson

Methods

gparseJSONf :: Settings -> Bool -> Bool -> Bool -> StateT [Value] Parser ((f :+: g) a)

(GfromJson f, GfromJson g) => GfromJson (f :*: g)

Defined in Generics.Generic.Aeson

Methods

gparseJSONf :: Settings -> Bool -> Bool -> Bool -> StateT [Value] Parser ((f :*: g) a)

GfromJson f => GfromJson (M1 D c f)

Defined in Generics.Generic.Aeson

Methods

gparseJSONf :: Settings -> Bool -> Bool -> Bool -> StateT [Value] Parser (M1 D c f a)

(Constructor c, GfromJson f) => GfromJson (M1 C c f)

Defined in Generics.Generic.Aeson

Methods

gparseJSONf :: Settings -> Bool -> Bool -> Bool -> StateT [Value] Parser (M1 C c f a)

(Selector c, FromJSON a) => GfromJson (M1 S c (K1 i (Maybe a) :: Type -> Type))

Defined in Generics.Generic.Aeson

Methods

gparseJSONf :: Settings -> Bool -> Bool -> Bool -> StateT [Value] Parser (M1 S c (K1 i (Maybe a)) a0)

(Selector c, GfromJson f) => GfromJson (M1 S c f)

Defined in Generics.Generic.Aeson

Methods

gparseJSONf :: Settings -> Bool -> Bool -> Bool -> StateT [Value] Parser (M1 S c f a)

formatLabel :: Settings -> Text -> Text

Lowercases the first letter and strips leading and trailing underscores.

data Settings

Constructors

Settings

Fields

• stripPrefix :: Maybe String

Instances

Show Settings

Defined in Generics.Generic.Aeson.Util

Methods

showsPrec :: Int -> Settings -> ShowS

show :: Settings -> String

showList :: [Settings] -> ShowS

defaultSettings :: Settings

gtoJsonWithSettings :: forall a. (Generic a, GtoJson (Rep a), ConNames (Rep a), GIsEnum (Rep a)) => Settings -> a -> Value

gparseJsonWithSettings :: forall a. (Generic a, GfromJson (Rep a), ConNames (Rep a), GIsEnum (Rep a)) => Settings -> Value -> Parser a