client.hs

#!/usr/bin/env nix-shell
#!nix-shell -i runghc -p "haskellPackages.ghcWithPackages (pkgs: with pkgs; [servant-generic  servant-client])"
#!nix-shell -I nixpkgs=http://nixos.org/channels/nixpkgs-unstable/nixexprs.tar.xz

{-# 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 :> ToServant (SubSite route)
  } deriving Generic


data SubSite route = SubSite
  { home :: route :-
      Get '[JSON] Text
  }

type UserAPI = ToServant (Site AsApi)

userAPI :: Proxy UserAPI
userAPI = Proxy

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

myClient :: Site AsClient
myClient = fromServant (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