horriblehaskell.hs

{-# LANGUAGE DuplicateRecordFields #-}

-- how to resolve the duplication in CreateUser, BasicUser and UpdateUser
-- without changing everything to `Maybe String`? 

data Address = Address { street :: String
                       , zip :: String
                       , city :: String
                       , state :: String
                       } deriving (Show)

data CreateUser = CreateUser { first :: String
                             , last :: String
                             , address :: Address
                             } deriving (Show)

data UpdateUser = UpdateUser { id :: Int
                             , first :: Maybe String
                             , last :: Maybe String
                             , address :: Maybe Address
                             } deriving (Show)

data BasicUser = BasicUser { id :: Int
                           , first :: String
                           , last :: String
                           } deriving (Show)

createUser :: CreateUser -> Int
createUser (CreateUser { first = _, last = _, address = _}) = 99

updateUser :: UpdateUser -> Bool
updateUser (UpdateUser { id = _, first = _, last = _, address = _}) = True

findBasicUser :: Int -> BasicUser
findBasicUser id = BasicUser{id = id, first = "Joe", last = "Smith"}

main :: IO ()
main = putStrLn "hello, world"