Data.Aeson.Schema.Utils.Sum

The SumType data type that represents a sum type consisting of types specified in a type-level list.

Documentation

data SumType (types :: [Type]) where

Represents a sum type.

Loads the first type that successfully parses the JSON value.

Example:

 data Owl = Owl
 data Cat = Cat
 data Toad = Toad
 type Animal = SumType '[Owl, Cat, Toad]

 Here Owl                         :: Animal
 There (Here Cat)                 :: Animal
 There (There (Here Toad))        :: Animal

 {- Fails at compile-time
 Here True                        :: Animal
 Here Cat                         :: Animal
 There (Here Owl)                 :: Animal
 There (There (There (Here Owl))) :: Animal
 -}
 

Constructors

Here :: forall x xs. x -> SumType (x ': xs)

There :: forall x xs. SumType xs -> SumType (x ': xs)

Instances

(FromJSON x, FromJSON (SumType xs)) => FromJSON (SumType (x ': xs))

Defined in Data.Aeson.Schema.Utils.Sum

Methods

parseJSON :: Value -> Parser (SumType (x ': xs))

parseJSONList :: Value -> Parser [SumType (x ': xs)]

omittedField :: Maybe (SumType (x ': xs))

FromJSON (SumType ('[] :: [Type]))

Defined in Data.Aeson.Schema.Utils.Sum

Methods

parseJSON :: Value -> Parser (SumType '[])

parseJSONList :: Value -> Parser [SumType '[]]

omittedField :: Maybe (SumType '[])

(ToJSON x, ToJSON (SumType xs)) => ToJSON (SumType (x ': xs))

Defined in Data.Aeson.Schema.Utils.Sum

Methods

toJSON :: SumType (x ': xs) -> Value

toEncoding :: SumType (x ': xs) -> Encoding

toJSONList :: [SumType (x ': xs)] -> Value

toEncodingList :: [SumType (x ': xs)] -> Encoding

omitField :: SumType (x ': xs) -> Bool

ToJSON (SumType ('[] :: [Type]))

Defined in Data.Aeson.Schema.Utils.Sum

Methods

toJSON :: SumType '[] -> Value

toEncoding :: SumType '[] -> Encoding

toJSONList :: [SumType '[]] -> Value

toEncodingList :: [SumType '[]] -> Encoding

omitField :: SumType '[] -> Bool

(Show x, Show (SumType xs)) => Show (SumType (x ': xs))

Defined in Data.Aeson.Schema.Utils.Sum

Methods

showsPrec :: Int -> SumType (x ': xs) -> ShowS

show :: SumType (x ': xs) -> String

showList :: [SumType (x ': xs)] -> ShowS

Show (SumType ('[] :: [Type]))

Defined in Data.Aeson.Schema.Utils.Sum

Methods

showsPrec :: Int -> SumType '[] -> ShowS

show :: SumType '[] -> String

showList :: [SumType '[]] -> ShowS

(Eq x, Eq (SumType xs)) => Eq (SumType (x ': xs))

Defined in Data.Aeson.Schema.Utils.Sum

Methods

(==) :: SumType (x ': xs) -> SumType (x ': xs) -> Bool

(/=) :: SumType (x ': xs) -> SumType (x ': xs) -> Bool

Eq (SumType ('[] :: [Type]))

Defined in Data.Aeson.Schema.Utils.Sum

Methods

(==) :: SumType '[] -> SumType '[] -> Bool

(/=) :: SumType '[] -> SumType '[] -> Bool

(Ord x, Ord (SumType xs)) => Ord (SumType (x ': xs))

Defined in Data.Aeson.Schema.Utils.Sum

Methods

compare :: SumType (x ': xs) -> SumType (x ': xs) -> Ordering

(<) :: SumType (x ': xs) -> SumType (x ': xs) -> Bool

(<=) :: SumType (x ': xs) -> SumType (x ': xs) -> Bool

(>) :: SumType (x ': xs) -> SumType (x ': xs) -> Bool

(>=) :: SumType (x ': xs) -> SumType (x ': xs) -> Bool

max :: SumType (x ': xs) -> SumType (x ': xs) -> SumType (x ': xs)

min :: SumType (x ': xs) -> SumType (x ': xs) -> SumType (x ': xs)

Ord (SumType ('[] :: [Type]))

Defined in Data.Aeson.Schema.Utils.Sum

Methods

compare :: SumType '[] -> SumType '[] -> Ordering

(<) :: SumType '[] -> SumType '[] -> Bool

(<=) :: SumType '[] -> SumType '[] -> Bool

(>) :: SumType '[] -> SumType '[] -> Bool

(>=) :: SumType '[] -> SumType '[] -> Bool

max :: SumType '[] -> SumType '[] -> SumType '[]

min :: SumType '[] -> SumType '[] -> SumType '[]

fromSumType :: (IsInRange n types, 'Just result ~ GetIndex n types, FromSumType n types result) => proxy n -> SumType types -> Maybe result

Extract a value from a SumType

Example:

 type Animal = SumType '[Owl, Cat, Toad]
 let someAnimal = ... :: Animal

 fromSumType (Proxy :: Proxy 0) someAnimal :: Maybe Owl
 fromSumType (Proxy :: Proxy 1) someAnimal :: Maybe Cat
 fromSumType (Proxy :: Proxy 2) someAnimal :: Maybe Toad

 -- Compile-time error
 -- fromSumType (Proxy :: Proxy 3) someAnimal