Named-based selection of sub-API

servant-server/example/greet.hs

@@ -85,7 +85,7 @@ server = (helloH :<|> postGreetH :<|> deleteGreetH :<|> otherRoutes) :<|> redire
           (\buildPath -> buildPath "Nicolas" (Just True))
 
         redirect _ = pure $
-          RedirectOf (Proxy @("bye" :> Capture "name" Text :> Get '[JSON] Text))
+          RedirectOf (namedRoute @"bye" @OtherRoutes)
           (\buildPath -> buildPath "Gaël")
 
 -- Turn the server into a WAI app. 'serve' is provided by servant,

servant/src/Servant/API.hs

@@ -143,7 +143,7 @@ import           Servant.API.UVerb
 import           Servant.API.Vault
                  (Vault)
 import           Servant.API.NamedRoutes
-                 (NamedRoutes)
+                 (NamedRoutes, namedRoute)
 import           Servant.API.Verbs
                  (Delete, DeleteAccepted, DeleteNoContent,
                  DeleteNonAuthoritative, Get, GetAccepted, GetNoContent,

servant/src/Servant/API/NamedRoutes.hs

@@ -1,10 +1,28 @@
-{-# LANGUAGE KindSignatures #-}
-{-# OPTIONS_HADDOCK not-home    #-}
+{-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE DataKinds           #-}
+{-# LANGUAGE KindSignatures      #-}
+{-# LANGUAGE ExplicitForAll      #-}
+{-# LANGUAGE TypeApplications    #-}
+{-# OPTIONS_HADDOCK not-home     #-}
 
 module Servant.API.NamedRoutes (
     -- * NamedRoutes combinator
     NamedRoutes
+    -- * Term-level helpers
+  , namedRoute
   ) where
 
+import Data.Proxy (Proxy(..))
+import GHC.Records (HasField)
+import GHC.TypeLits (Symbol)
+
+import Servant.API.Generic (AsApi)
+
+namedRoute
+  :: forall (field :: Symbol) (api :: * -> *) a.
+     HasField field (api AsApi) a
+  => Proxy a
+namedRoute = Proxy
+
 -- | Combinator for embedding a record of named routes into a Servant API type.
 data NamedRoutes (api :: * -> *)

servant/src/Servant/API/TypeLevel.hs

@@ -75,8 +75,6 @@ import           Servant.API.UVerb
 import           GHC.TypeLits
                  (ErrorMessage (..), TypeError)
 
-
-
 -- * API predicates
 
 -- | Flatten API into a list of endpoints.