servant/servant-js
2016-04-14 17:30:38 +08:00
..
examples stylish haskell changes 2015-08-18 00:07:12 +02:00
include less OverlappingInstances noise 2016-01-04 13:09:11 -05:00
src/Servant [servant-foreign] Parameterise type classes with a foreign representation type 2016-03-14 10:34:53 +13:00
test Merge pull request #404 from haskell-servant/base-compat 2016-03-18 13:53:13 +01:00
CHANGELOG.md Update servant-js changelog 2016-03-19 13:41:27 +01:00
docs.sh Replace servant-jquery with servant-js in remaining files 2015-11-02 19:59:46 +01:00
LICENSE Change copyright to servant contributors 2016-01-20 16:58:29 +01:00
README.md [servant-js] README-md - Fix broken link 2015-12-01 00:38:37 -05:00
servant-js.cabal version bump 2016-04-14 17:30:38 +08:00
Setup.hs stylish haskell changes 2015-08-18 00:07:12 +02:00
tinc.yaml Use tinc on travis 2015-11-05 09:32:13 +08:00
TODO.md rename servant-jquery to servant-js, Servant.JQuery to Servant.JS 2015-07-22 19:25:02 +02:00

servant-js

servant

This library lets you derive automatically Javascript functions that let you query each endpoint of a servant webservice.

It contains a powerful system allowing you to generate functions for several frameworks (Angular, AXios, JQuery) as well as vanilla (framework-free) javascript code.

Example

Read more about the following example here.

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}

import Control.Concurrent.STM
import Control.Monad.IO.Class
import Data.Aeson
import Data.Proxy
import GHC.Generics
import Network.Wai.Handler.Warp (run)
import Servant
import Servant.JS
import System.FilePath

-- * A simple Counter data type
newtype Counter = Counter { value :: Int }
  deriving (Generic, Show, Num)

instance ToJSON Counter

-- * Shared counter operations

-- Creating a counter that starts from 0
newCounter :: IO (TVar Counter)
newCounter = newTVarIO 0

-- Increasing the counter by 1
counterPlusOne :: MonadIO m => TVar Counter -> m Counter
counterPlusOne counter = liftIO . atomically $ do
  oldValue <- readTVar counter
  let newValue = oldValue + 1
  writeTVar counter newValue
  return newValue

currentValue :: MonadIO m => TVar Counter -> m Counter
currentValue counter = liftIO $ readTVarIO counter

-- * Our API type
type TestApi = "counter" :> Post '[JSON] Counter -- endpoint for increasing the counter
          :<|> "counter" :> Get  '[JSON] Counter -- endpoint to get the current value

type TestApi' = TestApi -- The API we want a JS handler for
           :<|> Raw     -- used for serving static files

-- this proxy only targets the proper endpoints of our API,
-- not the static file serving bit
testApi :: Proxy TestApi
testApi = Proxy

-- this proxy targets everything
testApi' :: Proxy TestApi'
testApi' = Proxy

-- * Server-side handler

-- where our static files reside
www :: FilePath
www = "examples/www"

-- defining handlers
server :: TVar Counter -> Server TestApi
server counter = counterPlusOne counter     -- (+1) on the TVar
            :<|> currentValue counter       -- read the TVar

server' :: TVar Counter -> Server TestApi'
server counter = server counter
            :<|> serveDirectory www         -- serve static files

runServer :: TVar Counter -- ^ shared variable for the counter
          -> Int          -- ^ port the server should listen on
          -> IO ()
runServer var port = run port (serve testApi' $ server' var)

main :: IO ()
main = do
  -- write the JS code to www/api.js at startup
  writeJSForAPI testApi jquery (www </> "api.js")

  -- setup a shared counter
  cnt <- newCounter

  -- listen to requests on port 8080
  runServer cnt 8080