How to parse array into tuple with aeson?
问题 If I have an array ["addTask", {"id": "1", "description": "d", "dependsOn": [], "dependentTasks": []}] . data Task = Task { id :: String , description :: String , dependsOn :: [String] , dependentTasks :: [String] } deriving (Eq, Show, Generic, ToJSON, FromJSON) type Change = Storage -> Storage addTask :: Task -> Change addTask (Task id desc dep dept) = insert id (Task id desc dep dept) How can I create a parser that would produce a addTask from that? instance FromJSON (Storage -> Storage)