servant/servant-examples/tutorial/T1.hs

{-# LANGUAGE DataKinds     #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE TypeFamilies  #-}
{-# LANGUAGE TypeOperators #-}
module T1 where

import           Data.Aeson
import           Data.Time.Calendar
import           GHC.Generics
import           Network.Wai
import           Servant

data User = User
  { name              :: String
  , age               :: Int
  , email             :: String
  , registration_date :: Day
  } deriving (Eq, Show, Generic)

-- orphan ToJSON instance for Day. necessary to derive one for User
instance ToJSON Day where
  -- display a day in YYYY-mm-dd format
  toJSON d = toJSON (showGregorian d)

instance ToJSON User

type UserAPI = "users" :> Get '[JSON] [User]

users :: [User]
users =
  [ User "Isaac Newton"    372 "isaac@newton.co.uk" (fromGregorian 1683  3 1)
  , User "Albert Einstein" 136 "ae@mc2.org"         (fromGregorian 1905 12 1)
  ]

userAPI :: Proxy UserAPI
userAPI = Proxy

server :: Server UserAPI
server = return users

app :: Application
app = serve userAPI server