servant-generic-client.hs

#!/usr/bin/env nix-shell
#!nix-shell -i runghc -p "haskellPackages.ghcWithPackages (pkgs: with pkgs; [servant-generic  servant-client])"

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE UndecidableInstances #-}
{-# LANGUAGE OverloadedStrings #-}

import Data.Aeson.Types
import Data.Text
import Data.Time (UTCTime)
import Data.Time.Calendar
import GHC.Generics
import Servant.API
import Servant
import Servant.Client
import Servant.Generic
import Network.HTTP.Client (newManager, defaultManagerSettings)


data Site route = Site
  { about :: route :-
      Capture "x" Text :> Get '[JSON] Text
  , faq :: route :-
      Capture "x" Int :> Get '[JSON] Int
  } deriving Generic


type UserAPI = ToServant (Site AsApi)

userAPI :: Proxy UserAPI
userAPI = Proxy

data AsClient
type instance AsClient :- api = Client ClientM api

myClient :: Site AsClient
myClient = Site
  { about = fromServant :: Text -> ClientM Text
  , faq = fromServant :: Int -> ClientM Int
  }

-- xxx = client userAPI

main :: IO ()
main = do
  manager <- newManager defaultManagerSettings
  let env = mkClientEnv manager $ BaseUrl Http "localhost" 8090 ""

  res <- runClientM (about myClient 3) env
  case res of
    Left err -> putStrLn $ "Error: " ++ show err
    Right books -> print books


-- https://github.com/chpatrick/servant-generic/pull/2/files