将记录中的构造函数转换为aeson haskell中的自定义json字符串

data Person = Person
  { name :: String
  , age :: Int
  }

import Data.Aeson (ToJSON, FromJSON, toJSON, parseJSON, object, (.=), withObject, (.:))

instance ToJSON Person where
  toJSON (Person name age) =
    object ["name" .= name, "age" .= age]

instance FromJSON Person where
  parseJSON = withObject "Person" $ \v ->
    Person <$> v .: "name" <*> v .: "age"

import Data.Aeson (encode)

person :: Person
person = Person "John Doe" 30

jsonString :: ByteString
jsonString = encode person

import Data.Aeson (decode)

decodedPerson :: Maybe Person
decodedPerson = decode jsonString