@@ -1,23 +1,24 @@
1−{-# LANGUAGE CPP #-}
1+{-# LANGUAGE AllowAmbiguousTypes #-}
2{-# LANGUAGE ConstraintKinds #-}
2{-# LANGUAGE ConstraintKinds #-}
3{-# LANGUAGE DataKinds #-}
4{-# LANGUAGE DataKinds #-}
4{-# LANGUAGE DeriveDataTypeable #-}
5{-# LANGUAGE DeriveDataTypeable #-}
5{-# LANGUAGE FlexibleContexts #-}
6{-# LANGUAGE FlexibleContexts #-}
6{-# LANGUAGE FlexibleInstances #-}
7{-# LANGUAGE FlexibleInstances #-}
8+{-# LANGUAGE InstanceSigs #-}
9+{-# LANGUAGE LambdaCase #-}
7{-# LANGUAGE MultiParamTypeClasses #-}
10{-# LANGUAGE MultiParamTypeClasses #-}
8{-# LANGUAGE OverloadedStrings #-}
11{-# LANGUAGE OverloadedStrings #-}
9{-# LANGUAGE PolyKinds #-}
12{-# LANGUAGE PolyKinds #-}
13+{-# LANGUAGE QuantifiedConstraints #-}
10{-# LANGUAGE RankNTypes #-}
14{-# LANGUAGE RankNTypes #-}
11{-# LANGUAGE ScopedTypeVariables #-}
15{-# LANGUAGE ScopedTypeVariables #-}
12{-# LANGUAGE TupleSections #-}
16{-# LANGUAGE TupleSections #-}
17+{-# LANGUAGE TypeApplications #-}
13{-# LANGUAGE TypeFamilies #-}
18{-# LANGUAGE TypeFamilies #-}
14{-# LANGUAGE TypeOperators #-}
19{-# LANGUAGE TypeOperators #-}
15{-# LANGUAGE UndecidableInstances #-}
20{-# LANGUAGE UndecidableInstances #-}
17−#if MIN_VERSION_base(4,9,0) && __GLASGOW_HASKELL__ >= 802
18−#define HAS_TYPE_ERROR
21module Servant.Server.Internal
22module Servant.Server.Internal
22 ( module Servant.Server.Internal
23 ( module Servant.Server.Internal
23 , module Servant.Server.Internal.BasicAuth
24 , module Servant.Server.Internal.BasicAuth
@@ -35,13 +36,15 @@ module Servant.Server.Internal
35import Control.Monad
36import Control.Monad
36 (join, when)
37 (join, when)
37import Control.Monad.Trans
38import Control.Monad.Trans
38− (liftIO)
39+ (liftIO, lift)
39import Control.Monad.Trans.Resource
40import Control.Monad.Trans.Resource
40− (runResourceT)
41+ (runResourceT, ReleaseKey)
41import qualified Data.ByteString as B
43import qualified Data.ByteString as B
42import qualified Data.ByteString.Builder as BB
44import qualified Data.ByteString.Builder as BB
43import qualified Data.ByteString.Char8 as BC8
45import qualified Data.ByteString.Char8 as BC8
44import qualified Data.ByteString.Lazy as BL
46import qualified Data.ByteString.Lazy as BL
47+import Data.Constraint (Constraint, Dict(..))
45import Data.Either
48import Data.Either
46 (partitionEithers)
49 (partitionEithers)
47import Data.Maybe
50import Data.Maybe
@@ -54,15 +57,16 @@ import Data.Tagged
54 (Tagged (..), retag, untag)
57 (Tagged (..), retag, untag)
55import qualified Data.Text as T
58import qualified Data.Text as T
56import Data.Typeable
59import Data.Typeable
57import GHC.TypeLits
61import GHC.TypeLits
58− (KnownNat, KnownSymbol, natVal, symbolVal)
62+ (KnownNat, KnownSymbol, TypeError, symbolVal)
59import qualified Network.HTTP.Media as NHM
63import qualified Network.HTTP.Media as NHM
60import Network.HTTP.Types hiding
64import Network.HTTP.Types hiding
61 (Header, ResponseHeaders)
65 (Header, ResponseHeaders)
62import Network.Socket
66import Network.Socket
63 (SockAddr)
67 (SockAddr)
64import Network.Wai
68import Network.Wai
65− (Application, Request, httpVersion, isSecure, lazyRequestBody,
69+ (Application, Request, Response, ResponseReceived, httpVersion, isSecure, lazyRequestBody,
66 queryString, remoteHost, getRequestBodyChunk, requestHeaders,
70 queryString, remoteHost, getRequestBodyChunk, requestHeaders,
67 requestMethod, responseLBS, responseStream, vault)
71 requestMethod, responseLBS, responseStream, vault)
68import Prelude ()
72import Prelude ()
@@ -72,10 +76,11 @@ import Servant.API
72 CaptureAll, Description, EmptyAPI, Fragment,
76 CaptureAll, Description, EmptyAPI, Fragment,
73 FramingRender (..), FramingUnrender (..), FromSourceIO (..),
77 FramingRender (..), FramingUnrender (..), FromSourceIO (..),
74 Header', If, IsSecure (..), NoContentVerb, QueryFlag,
78 Header', If, IsSecure (..), NoContentVerb, QueryFlag,
75− QueryParam', QueryParams, Raw, ReflectMethod (reflectMethod),
79+ QueryParam', QueryParams, Raw, RawM, ReflectMethod (reflectMethod),
76 RemoteHost, ReqBody', SBool (..), SBoolI (..), SourceIO,
80 RemoteHost, ReqBody', SBool (..), SBoolI (..), SourceIO,
77 Stream, StreamBody', Summary, ToSourceIO (..), Vault, Verb,
81 Stream, StreamBody', Summary, ToSourceIO (..), Vault, Verb,
78− WithNamedContext)
82+ WithNamedContext, WithResource, NamedRoutes)
83+import Servant.API.Generic (GenericMode(..), ToServant, ToServantApi, GServantProduct, toServant, fromServant)
79import Servant.API.ContentTypes
84import Servant.API.ContentTypes
80 (AcceptHeader (..), AllCTRender (..), AllCTUnrender (..),
85 (AcceptHeader (..), AllCTRender (..), AllCTUnrender (..),
81 AllMime, MimeRender (..), MimeUnrender (..), NoContent,
86 AllMime, MimeRender (..), MimeUnrender (..), NoContent,
@@ -85,10 +90,15 @@ import Servant.API.Modifiers
85 unfoldRequestArgument)
90 unfoldRequestArgument)
86import Servant.API.ResponseHeaders
91import Servant.API.ResponseHeaders
87 (GetHeaders, Headers, getHeaders, getResponse)
92 (GetHeaders, Headers, getHeaders, getResponse)
93+import Servant.API.Status
88import qualified Servant.Types.SourceT as S
95import qualified Servant.Types.SourceT as S
96+import Servant.API.TypeErrors
89import Web.HttpApiData
97import Web.HttpApiData
90 (FromHttpApiData, parseHeader, parseQueryParam, parseUrlPiece,
98 (FromHttpApiData, parseHeader, parseQueryParam, parseUrlPiece,
91 parseUrlPieces)
99 parseUrlPieces)
93import Servant.Server.Internal.BasicAuth
103import Servant.Server.Internal.BasicAuth
94import Servant.Server.Internal.Context
104import Servant.Server.Internal.Context
@@ -101,14 +111,16 @@ import Servant.Server.Internal.RouteResult
101import Servant.Server.Internal.RoutingApplication
111import Servant.Server.Internal.RoutingApplication
102import Servant.Server.Internal.ServerError
112import Servant.Server.Internal.ServerError
104−#ifdef HAS_TYPE_ERROR
105import GHC.TypeLits
114import GHC.TypeLits
106 (ErrorMessage (..), TypeError)
115 (ErrorMessage (..), TypeError)
107import Servant.API.TypeLevel
116import Servant.API.TypeLevel
108 (AtLeastOneFragment, FragmentUnique)
117 (AtLeastOneFragment, FragmentUnique)
111class HasServer api context where
119class HasServer api context where
120+ -- | The type of a server for this API, given a monad to run effects in.
122+ -- Note that the result kind is @*@, so it is /not/ a monad transformer, unlike
123+ -- what the @T@ in the name might suggest.
112 type ServerT api (m :: * -> *) :: *
124 type ServerT api (m :: * -> *) :: *
@@ -170,7 +182,7 @@ instance (HasServer a context, HasServer b context) => HasServer (a :<|> b) cont
170-- > server = getBook
182-- > server = getBook
171-- > where getBook :: Text -> Handler Book
183-- > where getBook :: Text -> Handler Book
172-- > getBook isbn = ...
184-- > getBook isbn = ...
173−instance (KnownSymbol capture, FromHttpApiData a
185+instance (KnownSymbol capture, FromHttpApiData a, Typeable a
174 , HasServer api context, SBoolI (FoldLenient mods)
186 , HasServer api context, SBoolI (FoldLenient mods)
175 , HasContextEntry (MkContextWithErrorFormatter context) ErrorFormatters
187 , HasContextEntry (MkContextWithErrorFormatter context) ErrorFormatters
@@ -182,7 +194,7 @@ instance (KnownSymbol capture, FromHttpApiData a
182 hoistServerWithContext _ pc nt s = hoistServerWithContext (Proxy :: Proxy api) pc nt . s
194 hoistServerWithContext _ pc nt s = hoistServerWithContext (Proxy :: Proxy api) pc nt . s
184 route Proxy context d =
196 route Proxy context d =
185− CaptureRouter $
197+ CaptureRouter [hint] $
186 route (Proxy :: Proxy api)
198 route (Proxy :: Proxy api)
188 (addCapture d $ \ txt -> withRequest $ \ request ->
200 (addCapture d $ \ txt -> withRequest $ \ request ->
@@ -194,6 +206,7 @@ instance (KnownSymbol capture, FromHttpApiData a
195 rep = typeRep (Proxy :: Proxy Capture')
207 rep = typeRep (Proxy :: Proxy Capture')
196 formatError = urlParseErrorFormatter $ getContextEntry (mkContextWithErrorFormatter context)
208 formatError = urlParseErrorFormatter $ getContextEntry (mkContextWithErrorFormatter context)
209+ hint = CaptureHint (T.pack $ symbolVal $ Proxy @capture) (typeRep (Proxy :: Proxy a))
198-- | If you use 'CaptureAll' in one of the endpoints for your API,
211-- | If you use 'CaptureAll' in one of the endpoints for your API,
199-- this automatically requires your server-side handler to be a
212-- this automatically requires your server-side handler to be a
@@ -212,7 +225,7 @@ instance (KnownSymbol capture, FromHttpApiData a
212-- > server = getSourceFile
225-- > server = getSourceFile
213-- > where getSourceFile :: [Text] -> Handler Book
226-- > where getSourceFile :: [Text] -> Handler Book
214-- > getSourceFile pathSegments = ...
227-- > getSourceFile pathSegments = ...
215−instance (KnownSymbol capture, FromHttpApiData a
228+instance (KnownSymbol capture, FromHttpApiData a, Typeable a
216 , HasServer api context
229 , HasServer api context
217 , HasContextEntry (MkContextWithErrorFormatter context) ErrorFormatters
230 , HasContextEntry (MkContextWithErrorFormatter context) ErrorFormatters
@@ -224,7 +237,7 @@ instance (KnownSymbol capture, FromHttpApiData a
224 hoistServerWithContext _ pc nt s = hoistServerWithContext (Proxy :: Proxy api) pc nt . s
237 hoistServerWithContext _ pc nt s = hoistServerWithContext (Proxy :: Proxy api) pc nt . s
226 route Proxy context d =
239 route Proxy context d =
227− CaptureAllRouter $
240+ CaptureAllRouter [hint] $
228 route (Proxy :: Proxy api)
241 route (Proxy :: Proxy api)
230 (addCapture d $ \ txts -> withRequest $ \ request ->
243 (addCapture d $ \ txts -> withRequest $ \ request ->
@@ -235,6 +248,43 @@ instance (KnownSymbol capture, FromHttpApiData a
236 rep = typeRep (Proxy :: Proxy CaptureAll)
249 rep = typeRep (Proxy :: Proxy CaptureAll)
237 formatError = urlParseErrorFormatter $ getContextEntry (mkContextWithErrorFormatter context)
250 formatError = urlParseErrorFormatter $ getContextEntry (mkContextWithErrorFormatter context)
251+ hint = CaptureHint (T.pack $ symbolVal $ Proxy @capture) (typeRep (Proxy :: Proxy [a]))
253+-- | If you use 'WithResource' in one of the endpoints for your API Servant
254+-- will provide the handler for this endpoint an argument of the specified type.
255+-- The lifespan of this resource will be automatically managed by Servant. This
256+-- resource will be created before the handler starts and it will be destoyed
257+-- after it ends. A new resource is created for each request to the endpoint.
259+-- The creation and destruction are done using a 'Data.Acquire.Acquire'
260+-- provided via server 'Context'.
264+-- > type MyApi = WithResource Handle :> "writeToFile" :> Post '[JSON] NoContent
266+-- > server :: Server MyApi
267+-- > server = writeToFile
268+-- > where writeToFile :: (ReleaseKey, Handle) -> Handler NoContent
269+-- > writeToFile (_, h) = hPutStrLn h "message"
271+-- In addition to the resource, the handler will also receive a 'ReleaseKey'
272+-- which can be used to deallocate the resource before the end of the request
275+instance (HasServer api ctx, HasContextEntry ctx (Acquire a))
276+ => HasServer (WithResource a :> api) ctx where
278+ type ServerT (WithResource a :> api) m = (ReleaseKey, a) -> ServerT api m
280+ hoistServerWithContext _ pc nt s = hoistServerWithContext (Proxy @api) pc nt . s
282+ route Proxy context d = route (Proxy @api) context (d `addParameterCheck` allocateResource)
284+ allocateResource :: DelayedIO (ReleaseKey, a)
285+ allocateResource = DelayedIO $ lift $ allocateAcquire (getContextEntry context)
239allowedMethodHead :: Method -> Request -> Bool
289allowedMethodHead :: Method -> Request -> Bool
240allowedMethodHead method request = method == methodGet && requestMethod request == methodHead
290allowedMethodHead method request = method == methodGet && requestMethod request == methodHead
@@ -298,7 +348,7 @@ instance {-# OVERLAPPABLE #-}
299 route Proxy _ = methodRouter ([],) method (Proxy :: Proxy ctypes) status
349 route Proxy _ = methodRouter ([],) method (Proxy :: Proxy ctypes) status
300 where method = reflectMethod (Proxy :: Proxy method)
350 where method = reflectMethod (Proxy :: Proxy method)
301− status = toEnum . fromInteger $ natVal (Proxy :: Proxy status)
351+ status = statusFromNat (Proxy :: Proxy status)
303instance {-# OVERLAPPING #-}
353instance {-# OVERLAPPING #-}
304 ( AllCTRender ctypes a, ReflectMethod method, KnownNat status
354 ( AllCTRender ctypes a, ReflectMethod method, KnownNat status
@@ -310,7 +360,7 @@ instance {-# OVERLAPPING #-}
311 route Proxy _ = methodRouter (\x -> (getHeaders x, getResponse x)) method (Proxy :: Proxy ctypes) status
361 route Proxy _ = methodRouter (\x -> (getHeaders x, getResponse x)) method (Proxy :: Proxy ctypes) status
312 where method = reflectMethod (Proxy :: Proxy method)
362 where method = reflectMethod (Proxy :: Proxy method)
313− status = toEnum . fromInteger $ natVal (Proxy :: Proxy status)
363+ status = statusFromNat (Proxy :: Proxy status)
315instance (ReflectMethod method) =>
365instance (ReflectMethod method) =>
316 HasServer (NoContentVerb method) context where
366 HasServer (NoContentVerb method) context where
@@ -331,7 +381,7 @@ instance {-# OVERLAPPABLE #-}
332 route Proxy _ = streamRouter ([],) method status (Proxy :: Proxy framing) (Proxy :: Proxy ctype)
382 route Proxy _ = streamRouter ([],) method status (Proxy :: Proxy framing) (Proxy :: Proxy ctype)
333 where method = reflectMethod (Proxy :: Proxy method)
383 where method = reflectMethod (Proxy :: Proxy method)
334− status = toEnum . fromInteger $ natVal (Proxy :: Proxy status)
384+ status = statusFromNat (Proxy :: Proxy status)
337instance {-# OVERLAPPING #-}
387instance {-# OVERLAPPING #-}
@@ -345,7 +395,7 @@ instance {-# OVERLAPPING #-}
346 route Proxy _ = streamRouter (\x -> (getHeaders x, getResponse x)) method status (Proxy :: Proxy framing) (Proxy :: Proxy ctype)
396 route Proxy _ = streamRouter (\x -> (getHeaders x, getResponse x)) method status (Proxy :: Proxy framing) (Proxy :: Proxy ctype)
347 where method = reflectMethod (Proxy :: Proxy method)
397 where method = reflectMethod (Proxy :: Proxy method)
348− status = toEnum . fromInteger $ natVal (Proxy :: Proxy status)
398+ status = statusFromNat (Proxy :: Proxy status)
351streamRouter :: forall ctype a c chunk env framing. (MimeRender ctype chunk, FramingRender framing, ToSourceIO chunk a) =>
401streamRouter :: forall ctype a c chunk env framing. (MimeRender ctype chunk, FramingRender framing, ToSourceIO chunk a) =>
@@ -603,6 +653,35 @@ instance HasServer Raw context where
603 Fail a -> respond $ Fail a
653 Fail a -> respond $ Fail a
604 FailFatal e -> respond $ FailFatal e
654 FailFatal e -> respond $ FailFatal e
656+-- | Just pass the request to the underlying application and serve its response.
660+-- > type MyApi = "images" :> Raw
662+-- > server :: Server MyApi
663+-- > server = serveDirectory "/var/www/images"
664+instance HasServer RawM context where
665+ type ServerT RawM m = Request -> (Response -> IO ResponseReceived) -> m ResponseReceived
670+ -> Delayed env (Request -> (Response -> IO ResponseReceived) -> Handler ResponseReceived) -> Router env
671+ route _ _ handleDelayed = RawRouter $ \env request respond -> runResourceT $ do
672+ routeResult <- runDelayed handleDelayed env request
673+ let respond' = liftIO . respond
674+ liftIO $ case routeResult of
675+ Route handler -> runHandler (handler request (respond . Route)) >>=
677+ Left e -> respond' $ FailFatal e
679+ Fail e -> respond' $ Fail e
680+ FailFatal e -> respond' $ FailFatal e
682+ hoistServerWithContext _ _ f srvM = \req respond -> f (srvM req respond)
606-- | If you use 'ReqBody' in one of the endpoints for your API,
685-- | If you use 'ReqBody' in one of the endpoints for your API,
607-- this automatically requires your server-side handler to be a function
686-- this automatically requires your server-side handler to be a function
608-- that takes an argument of the type specified by 'ReqBody'.
687-- that takes an argument of the type specified by 'ReqBody'.
@@ -784,7 +863,7 @@ instance ( KnownSymbol realm
784-- * helpers
863-- * helpers
786ct_wildcard :: B.ByteString
865ct_wildcard :: B.ByteString
787−ct_wildcard = "*" <> "/" <> "*" -- Because CPP
866+ct_wildcard = "*" <> "/" <> "*"
789getAcceptHeader :: Request -> AcceptHeader
868getAcceptHeader :: Request -> AcceptHeader
790getAcceptHeader = AcceptHeader . fromMaybe ct_wildcard . lookup hAccept . requestHeaders
869getAcceptHeader = AcceptHeader . fromMaybe ct_wildcard . lookup hAccept . requestHeaders
@@ -812,39 +891,19 @@ instance (HasContextEntry context (NamedContext name subContext), HasServer subA
812 hoistServerWithContext _ _ nt s = hoistServerWithContext (Proxy :: Proxy subApi) (Proxy :: Proxy subContext) nt s
891 hoistServerWithContext _ _ nt s = hoistServerWithContext (Proxy :: Proxy subApi) (Proxy :: Proxy subContext) nt s
814-------------------------------------------------------------------------------
893-------------------------------------------------------------------------------
815−-- TypeError helpers
894+-- Custom type errors
816-------------------------------------------------------------------------------
895-------------------------------------------------------------------------------
818−#ifdef HAS_TYPE_ERROR
897+-- Erroring instance for 'HasServer' when a combinator is not fully applied
819−-- | This instance catches mistakes when there are non-saturated
898+instance TypeError (PartialApplication
820−-- type applications on LHS of ':>'.
899+#if __GLASGOW_HASKELL__ >= 904
821−--
900+ @(Type -> [Type] -> Constraint)
822−-- >>> serve (Proxy :: Proxy (Capture "foo" :> Get '[JSON] Int)) (error "...")
901+#endif
824−-- ...Expected something of kind Symbol or *, got: k -> l on the LHS of ':>'.
825−-- ...Maybe you haven't applied enough arguments to
826−-- ...Capture' '[] "foo"
829−-- >>> undefined :: Server (Capture "foo" :> Get '[JSON] Int)
831−-- ...Expected something of kind Symbol or *, got: k -> l on the LHS of ':>'.
832−-- ...Maybe you haven't applied enough arguments to
833−-- ...Capture' '[] "foo"
836−instance TypeError (HasServerArrowKindError arr) => HasServer ((arr :: k -> l) :> api) context
902+ HasServer arr) => HasServer ((arr :: a -> b) :> sub) context
838− type ServerT (arr :> api) m = TypeError (HasServerArrowKindError arr)
904+ type ServerT (arr :> sub) _ = TypeError (PartialApplication (HasServer :: * -> [*] -> Constraint) arr)
839− -- it doesn't really matter what sub route we peak
905+ route = error "unreachable"
840− route _ _ _ = error "servant-server panic: impossible happened in HasServer (arr :> api)"
841− hoistServerWithContext _ _ _ = id
906+ hoistServerWithContext _ _ _ _ = error "unreachable"
843−-- Cannot have TypeError here, otherwise use of this symbol will error :)
844−type HasServerArrowKindError arr =
845− 'Text "Expected something of kind Symbol or *, got: k -> l on the LHS of ':>'."
846− ':$$: 'Text "Maybe you haven't applied enough arguments to"
849-- | This instance prevents from accidentally using '->' instead of ':>'
908-- | This instance prevents from accidentally using '->' instead of ':>'
@@ -878,7 +937,19 @@ type HasServerArrowTypeError a b =
878 ':$$: 'ShowType a
937 ':$$: 'ShowType a
879 ':$$: 'Text "and"
938 ':$$: 'Text "and"
880 ':$$: 'ShowType b
939 ':$$: 'ShowType b
941+-- Erroring instances for 'HasServer' for unknown API combinators
943+-- XXX: This omits the @context@ parameter, e.g.:
945+-- "There is no instance for HasServer (Bool :> …)". Do we care ?
946+instance {-# OVERLAPPABLE #-} TypeError (NoInstanceForSub
947+#if __GLASGOW_HASKELL__ >= 904
948+ @(Type -> [Type] -> Constraint)
950+ HasServer ty) => HasServer (ty :> sub) context
952+instance {-# OVERLAPPABLE #-} TypeError (NoInstanceFor (HasServer api context)) => HasServer api context
883-- | Ignore @'Fragment'@ in server handlers.
954-- | Ignore @'Fragment'@ in server handlers.
884-- See <https://ietf.org/rfc/rfc2616.html#section-15.1.3> for more details.
955-- See <https://ietf.org/rfc/rfc2616.html#section-15.1.3> for more details.
@@ -891,11 +962,7 @@ type HasServerArrowTypeError a b =
891-- > server = getBooks
962-- > server = getBooks
892-- > where getBooks :: Handler [Book]
963-- > where getBooks :: Handler [Book]
893-- > getBooks = ...return all books...
964-- > getBooks = ...return all books...
894−#ifdef HAS_TYPE_ERROR
895instance (AtLeastOneFragment api, FragmentUnique (Fragment a1 :> api), HasServer api context)
965instance (AtLeastOneFragment api, FragmentUnique (Fragment a1 :> api), HasServer api context)
897−instance (HasServer api context)
899 => HasServer (Fragment a1 :> api) context where
966 => HasServer (Fragment a1 :> api) context where
900 type ServerT (Fragment a1 :> api) m = ServerT api m
967 type ServerT (Fragment a1 :> api) m = ServerT api m
@@ -905,3 +972,72 @@ instance (HasServer api context)
907-- >>> import Servant
974-- >>> import Servant
976+-- | A type that specifies that an API record contains a server implementation.
977+data AsServerT (m :: * -> *)
978+instance GenericMode (AsServerT m) where
979+ type AsServerT m :- api = ServerT api m
981+type AsServer = AsServerT Handler
984+-- | Set of constraints required to convert to / from vanilla server types.
985+type GServerConstraints api m =
986+ ( ToServant api (AsServerT m) ~ ServerT (ToServantApi api) m
987+ , GServantProduct (Rep (api (AsServerT m)))
990+-- | This class is a necessary evil: in the implementation of 'HasServer' for
991+-- @'NamedRoutes' api@, we essentially need the quantified constraint @forall
992+-- m. 'GServerConstraints' m@ to hold.
994+-- We cannot require do that directly as the definition of 'GServerConstraints'
995+-- contains type family applications ('Rep' and 'ServerT'). The trick is to hide
996+-- those type family applications behind a typeclass providing evidence for
997+-- @'GServerConstraints' api m@ in the form of a dictionary, and require that
998+-- @forall m. 'GServer' api m@ instead.
1000+-- Users shouldn't have to worry about this class, as the only possible instance
1001+-- is provided in this module for all record APIs.
1003+class GServer (api :: * -> *) (m :: * -> *) where
1004+ gServerProof :: Dict (GServerConstraints api m)
1007+ ( ToServant api (AsServerT m) ~ ServerT (ToServantApi api) m
1008+ , GServantProduct (Rep (api (AsServerT m)))
1009+ ) => GServer api m where
1010+ gServerProof = Dict
1013+ ( HasServer (ToServantApi api) context
1014+ , forall m. Generic (api (AsServerT m))
1015+ , forall m. GServer api m
1016+ ) => HasServer (NamedRoutes api) context where
1018+ type ServerT (NamedRoutes api) m = api (AsServerT m)
1021+ :: Proxy (NamedRoutes api)
1023+ -> Delayed env (api (AsServerT Handler))
1025+ route _ ctx delayed =
1026+ case gServerProof @api @Handler of
1027+ Dict -> route (Proxy @(ToServantApi api)) ctx (toServant <$> delayed)
1029+ hoistServerWithContext
1030+ :: forall m n. Proxy (NamedRoutes api)
1032+ -> (forall x. m x -> n x)
1033+ -> api (AsServerT m)
1034+ -> api (AsServerT n)
1035+ hoistServerWithContext _ pctx nat server =
1036+ case (gServerProof @api @m, gServerProof @api @n) of
1038+ fromServant servantSrvN
1040+ servantSrvM :: ServerT (ToServantApi api) m =
1042+ servantSrvN :: ServerT (ToServantApi api) n =
1043+ hoistServerWithContext (Proxy @(ToServantApi api)) pctx nat servantSrvM