servant/servant-http-streams/README.md
2019-02-06 12:15:30 +02:00

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# servant-client
![servant](https://raw.githubusercontent.com/haskell-servant/servant/master/servant.png)
This library lets you automatically derive Haskell functions that let you query each endpoint of a *servant* webservice.
## Example
``` haskell
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeOperators #-}
import Data.Proxy
import Data.Text
import Servant.API
import Servant.HttpStreams
type Book = Text
type MyApi = "books" :> Get '[JSON] [Book] -- GET /books
:<|> "books" :> ReqBody '[JSON] Book :> Post '[JSON] Book -- POST /books
myApi :: Proxy MyApi
myApi = Proxy
-- 'client' allows you to produce operations to query an API from a client.
postNewBook :: Book -> ClientM Book
getAllBooks :: ClientM [Book]
(getAllBooks :<|> postNewBook) = client myApi
-- the IOException happens already in withClientEnvIO
main' :: IO ()
main' = do
let burl = BaseUrl Http "localhost" 8081 ""
withClientEnvIO burl $ \env -> do
res <- runClientM getAllBooks env
case res of
Left err -> putStrLn $ "Error: " ++ show err
Right books -> print books
main :: IO ()
main = return ()
```