| Safe Haskell | None |
|---|---|
| Language | Haskell98 |
Generics.Generic.Aeson
Description
This module offers generic conversions to an 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.
Maybevalues are either an absent key, or the value.
See 'tests/Main.hs' for more examples.
- gtoJson :: forall a. (Generic a, GtoJson (Rep a), ConNames (Rep a), GIsEnum (Rep a)) => a -> Value
- gparseJson :: forall a. (Generic a, GfromJson (Rep a), ConNames (Rep a), GIsEnum (Rep a)) => Value -> Parser a
- class GtoJson f where
- class GfromJson f where
- formatLabel :: Settings -> Text -> Text
- data Settings = Settings {}
- 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
Documentation
gtoJson :: forall a. (Generic a, GtoJson (Rep a), ConNames (Rep a), GIsEnum (Rep a)) => a -> Value Source
gparseJson :: forall a. (Generic a, GfromJson (Rep a), ConNames (Rep a), GIsEnum (Rep a)) => Value -> Parser a Source
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)] Source
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 | |
| ToJSON c => GtoJson (K1 a c) | |
| (GtoJson f, GtoJson g) => GtoJson ((:+:) f g) | |
| (GtoJson f, GtoJson g) => GtoJson ((:*:) f g) | |
| GtoJson f => GtoJson (M1 D c f) | |
| (Constructor c, GtoJson f) => GtoJson (M1 C c f) | |
| (Selector c, ToJSON a) => GtoJson (M1 S c (K1 i (Maybe a))) | |
| (Selector c, GtoJson f) => GtoJson (M1 S c f) |
class GfromJson f where Source
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) Source
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 | |
| FromJSON c => GfromJson (K1 a c) | |
| (GfromJson f, GfromJson g) => GfromJson ((:+:) f g) | |
| (GfromJson f, GfromJson g) => GfromJson ((:*:) f g) | |
| GfromJson f => GfromJson (M1 D c f) | |
| (Constructor c, GfromJson f) => GfromJson (M1 C c f) | |
| (Selector c, FromJSON a) => GfromJson (M1 S c (K1 i (Maybe a))) | |
| (Selector c, GfromJson f) => GfromJson (M1 S c f) |
formatLabel :: Settings -> Text -> Text Source
Lowercases the first letter and strips leading and trailing underscores.