examples: add GS5

servant-examples/getting-started/GS5.hs

@@ -0,0 +1,37 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE TypeOperators #-}
+{-# LANGUAGE OverloadedStrings #-}
+module GS5 where
+
+import Control.Monad.IO.Class
+import Control.Monad.Trans.Either
+import Data.Aeson
+import GHC.Generics
+import Network.Wai
+import Servant
+import System.Directory
+
+type IOAPI = "myfile.txt" :> Get '[JSON] FileContent
+
+ioAPI :: Proxy IOAPI
+ioAPI = Proxy
+
+newtype FileContent = FileContent
+  { content :: String }
+  deriving Generic
+
+instance ToJSON FileContent
+
+server :: Server IOAPI
+server = do
+  exists <- liftIO (doesFileExist "myfile.txt")
+  if exists
+    then liftIO (readFile "myfile.txt") >>= return . FileContent
+    else left custom404Err
+
+  where custom404Err = err404 { errBody = "myfile.txt just isn't there, please leave this server alone." }
+
+app :: Application
+app = serve ioAPI server

servant-examples/getting-started/getting-started.hs

@@ -6,6 +6,7 @@ import qualified GS1
 import qualified GS2
 import qualified GS3
 import qualified GS4
+import qualified GS5
 
 app :: String -> Maybe Application
 app n = case n of
@@ -13,6 +14,7 @@ app n = case n of
   "2" -> Just GS2.app
   "3" -> Just GS3.app
   "4" -> Just GS4.app
+  "5" -> Just GS5.app
   _   -> Nothing
 
 main :: IO ()

servant-examples/servant-examples.cabal

@@ -19,12 +19,14 @@ executable getting-started
   build-depends:
       aeson >= 0.8
     , base >= 4.7
+    , directory
     , either
     , lucid
     , servant
     , servant-lucid
     , servant-server
     , time
+    , transformers
     , wai
     , warp
   hs-source-dirs: getting-started