Add EmptyAPI type

servant/servant.cabal

@@ -36,6 +36,7 @@ library
     Servant.API.BasicAuth
     Servant.API.Capture
     Servant.API.ContentTypes
+    Servant.API.Empty
     Servant.API.Experimental.Auth
     Servant.API.Header
     Servant.API.HttpVersion

servant/src/Servant/API/Empty.hs

@@ -0,0 +1,10 @@
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# OPTIONS_HADDOCK not-home    #-}
+module Servant.API.Empty(EmptyAPI(..)) where
+
+import           Data.Typeable    (Typeable)
+import           Prelude ()
+import           Prelude.Compat
+
+-- | An empty API: one which serves nothing.
+data EmptyAPI = EmptyAPI deriving (Typeable, Eq, Show, Bounded)