72 lines
2 KiB
Haskell
72 lines
2 KiB
Haskell
{-# LANGUAGE DataKinds #-}
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{-# LANGUAGE DeriveGeneric #-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE PolyKinds #-}
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{-# LANGUAGE TypeFamilies #-}
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{-# LANGUAGE TypeOperators #-}
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import Data.Aeson
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import Data.Monoid
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import Data.Proxy
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import Data.Text
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import GHC.Generics
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import Network.Wai
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import Network.Wai.Handler.Warp
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import Servant
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-- * Example
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-- | A greet message data type
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newtype Greet = Greet { _msg :: Text }
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deriving (Generic, Show)
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instance FromJSON Greet
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instance ToJSON Greet
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-- API specification
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type TestApi =
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-- GET /hello/:name?capital={true, false} returns a Greet as JSON
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"hello" :> Capture "name" Text :> QueryParam "capital" Bool :> Get '[JSON] Greet
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-- POST /greet with a Greet as JSON in the request body,
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-- returns a Greet as JSON
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:<|> "greet" :> ReqBody '[JSON] Greet :> Post '[JSON] Greet
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-- DELETE /greet/:greetid
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:<|> "greet" :> Capture "greetid" Text :> Delete '[JSON] ()
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testApi :: Proxy TestApi
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testApi = Proxy
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-- Server-side handlers.
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--
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-- There's one handler per endpoint, which, just like in the type
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-- that represents the API, are glued together using :<|>.
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--
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-- Each handler runs in the 'ExceptT ServantErr IO' monad.
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server :: Server TestApi
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server = helloH :<|> postGreetH :<|> deleteGreetH
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where helloH name Nothing = helloH name (Just False)
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helloH name (Just False) = return . Greet $ "Hello, " <> name
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helloH name (Just True) = return . Greet . toUpper $ "Hello, " <> name
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postGreetH greet = return greet
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deleteGreetH _ = return ()
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-- Turn the server into a WAI app. 'serve' is provided by servant,
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-- more precisely by the Servant.Server module.
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test :: Application
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test = serve testApi EmptyConfig server
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-- Run the server.
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--
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-- 'run' comes from Network.Wai.Handler.Warp
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runTestServer :: Port -> IO ()
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runTestServer port = run port test
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-- Put this all to work!
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main :: IO ()
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main = runTestServer 8001
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