servant/servant-machines/example/Main.hs
Oleg Grenrus 45c1cbdfd5 Refactor Stream stuff
- Introduce SourceT, which is simple variant of "correct `ListT`".
  There are another variants possible (like in `streaming`),
  but I'm not sure there's much real difference.

- Introduce `Codensity`. There's a flag if people don't want to depend
  on `kan-extensions`.

- `StreamGenerator` and `ResultStream` are both `SourceT`.
  `Stream` combinator in `servant-client` uses `Codensity` for CPS.

- Add servant-machines, servant-conduit, servant-pipes
- Add streaming cookbook: just code, no explanations.
- Add a script to run streaming 'benchmarks'
2018-11-05 15:48:47 +02:00

98 lines
3.1 KiB
Haskell

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE TypeOperators #-}
module Main (main) where
import Prelude ()
import Prelude.Compat
import Control.Concurrent
(threadDelay)
import Control.Monad.IO.Class
(MonadIO (..))
import qualified Data.ByteString as BS
import Data.Maybe
(fromMaybe)
import Data.Void
(Void)
import Network.HTTP.Client
(defaultManagerSettings, newManager)
import Network.Wai
(Application)
import System.Environment
(getArgs, lookupEnv)
import Text.Read
(readMaybe)
import Data.Machine
import Servant
import Servant.Client
import Servant.Machines ()
import qualified Network.Wai.Handler.Warp as Warp
type FastAPI = "get" :> Capture "num" Int :> StreamGet NewlineFraming JSON (MachineT IO (Is Void) Int)
type API = FastAPI
:<|> "slow" :> Capture "num" Int :> StreamGet NewlineFraming JSON (MachineT IO (Is Void) Int)
:<|> "proxy"
:> StreamBody NoFraming OctetStream (MachineT IO (Is Void) BS.ByteString)
:> StreamPost NoFraming OctetStream (MachineT IO (Is Void) BS.ByteString)
api :: Proxy API
api = Proxy
server :: Server API
server = fast :<|> slow :<|> proxy
where
fast n = liftIO $ do
putStrLn ("/get/" ++ show n)
return $ fastMachine n
slow n = liftIO $ do
putStrLn ("/slow/" ++ show n)
return $ slowMachine n
proxy c = liftIO $ do
putStrLn "/proxy"
return c
-- for some reason unfold leaks?
fastMachine m
| m < 0 = MachineT (return Stop)
| otherwise = MachineT (return (Yield m (fastMachine (m - 1))))
slowMachine m
| m < 0 = MachineT (return Stop)
| otherwise = MachineT $ do
threadDelay 1000000
return (Yield m (slowMachine (m - 1)))
app :: Application
app = serve api server
cli :: Client ClientM FastAPI
cli :<|> _ = client api
main :: IO ()
main = do
args <- getArgs
case args of
("server":_) -> do
putStrLn "Starting servant-machines:example at http://localhost:8000"
port <- fromMaybe 8000 . (>>= readMaybe) <$> lookupEnv "PORT"
Warp.run port app
("client":ns:_) -> do
n <- maybe (fail $ "not a number: " ++ ns) pure $ readMaybe ns
mgr <- newManager defaultManagerSettings
burl <- parseBaseUrl "http://localhost:8000/"
withClientM (cli n) (mkClientEnv mgr burl) $ \me -> case me of
Left err -> print err
Right m -> do
x <- runT $ fold (\p _ -> p + 1) (0 :: Int) <~ m
print x
_ -> do
putStrLn "Try:"
putStrLn "cabal new-run servant-machines:example server"
putStrLn "cabal new-run servant-machines:example client 10"
putStrLn "time curl -H 'Accept: application/json' localhost:8000/slow/5"