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App.hs
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App.hs
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{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE TypeOperators #-}
module App where
import Data.Aeson
import GHC.Generics
import Network.Wai
import Network.Wai.Handler.Warp
import Servant
import System.IO
-- * api
type ItemApi =
"item" :> Get '[JSON] [Item] :<|>
"item" :> Capture "itemId" Integer :> Get '[JSON] Item
itemApi :: Proxy ItemApi
itemApi = Proxy
-- * app
run :: IO ()
run = do
let port = 3000
settings =
setPort port $
setBeforeMainLoop (hPutStrLn stderr ("listening on port " ++ show port)) $
defaultSettings
runSettings settings =<< mkApp
mkApp :: IO Application
mkApp = return $ serve itemApi server
server :: Server ItemApi
server =
getItems :<|>
getItemById
getItems :: Handler [Item]
getItems = return [exampleItem]
getItemById :: Integer -> Handler Item
getItemById = \ case
0 -> return exampleItem
_ -> throwError err404
exampleItem :: Item
exampleItem = Item 0 "example item"
-- * item
data Item
= Item {
itemId :: Integer,
itemText :: String
}
deriving (Eq, Show, Generic)
instance ToJSON Item
instance FromJSON Item
data a + b = Foo a b
type X = Int + Bool