@@ -1,29 +1,29 @@
1−{-# LANGUAGE CPP #-}
1+{-# LANGUAGE AllowAmbiguousTypes #-}
22{-# LANGUAGE ConstraintKinds #-}
33{-# LANGUAGE DataKinds #-}
44{-# LANGUAGE DeriveDataTypeable #-}
55{-# LANGUAGE FlexibleContexts #-}
66{-# LANGUAGE FlexibleInstances #-}
7+{-# LANGUAGE InstanceSigs #-}
78{-# LANGUAGE MultiParamTypeClasses #-}
89{-# LANGUAGE OverloadedStrings #-}
910{-# LANGUAGE PolyKinds #-}
11+{-# LANGUAGE QuantifiedConstraints #-}
1012{-# LANGUAGE RankNTypes #-}
1113{-# LANGUAGE ScopedTypeVariables #-}
1214{-# LANGUAGE TupleSections #-}
15+{-# LANGUAGE TypeApplications #-}
1316{-# LANGUAGE TypeFamilies #-}
1417{-# LANGUAGE TypeOperators #-}
1518{-# LANGUAGE UndecidableInstances #-}
1619
17−#if MIN_VERSION_base(4,9,0) && __GLASGOW_HASKELL__ >= 802
18−#define HAS_TYPE_ERROR
19−#endif
20−
2120module Servant.Server.Internal
2221 ( module Servant.Server.Internal
2322 , module Servant.Server.Internal.BasicAuth
2423 , module Servant.Server.Internal.Context
2524 , module Servant.Server.Internal.Delayed
2625 , module Servant.Server.Internal.DelayedIO
26+ , module Servant.Server.Internal.ErrorFormatter
2727 , module Servant.Server.Internal.Handler
2828 , module Servant.Server.Internal.Router
2929 , module Servant.Server.Internal.RouteResult
@@ -41,12 +41,11 @@ import qualified Data.ByteString as B
4141import qualified Data.ByteString.Builder as BB
4242import qualified Data.ByteString.Char8 as BC8
4343import qualified Data.ByteString.Lazy as BL
44+import Data.Constraint (Constraint, Dict(..))
4445import Data.Either
4546 (partitionEithers)
4647import Data.Maybe
4748 (fromMaybe, isNothing, mapMaybe, maybeToList)
48−import Data.Semigroup
49− ((<>))
5049import Data.String
5150 (IsString (..))
5251import Data.String.Conversions
@@ -55,8 +54,9 @@ import Data.Tagged
5554 (Tagged (..), retag, untag)
5655import qualified Data.Text as T
5756import Data.Typeable
57+import GHC.Generics
5858import GHC.TypeLits
59− (KnownNat, KnownSymbol, natVal, symbolVal)
59+ (KnownNat, KnownSymbol, TypeError, symbolVal)
6060import qualified Network.HTTP.Media as NHM
6161import Network.HTTP.Types hiding
6262 (Header, ResponseHeaders)
@@ -64,47 +64,52 @@ import Network.Socket
6464 (SockAddr)
6565import Network.Wai
6666 (Application, Request, httpVersion, isSecure, lazyRequestBody,
67− queryString, remoteHost, requestBody, requestHeaders,
67+ queryString, remoteHost, getRequestBodyChunk, requestHeaders,
6868 requestMethod, responseLBS, responseStream, vault)
6969import Prelude ()
7070import Prelude.Compat
7171import Servant.API
7272 ((:<|>) (..), (:>), Accept (..), BasicAuth, Capture',
73− CaptureAll, Description, EmptyAPI, FramingRender (..),
74− FramingUnrender (..), FromSourceIO (..), Header', If,
75− IsSecure (..), QueryFlag, QueryParam', QueryParams, Raw,
76− ReflectMethod (reflectMethod), RemoteHost, ReqBody',
77− SBool (..), SBoolI (..), SourceIO, Stream, StreamBody',
78− Summary, ToSourceIO (..), Vault, Verb, NoContentVerb,
79− WithNamedContext)
73+ CaptureAll, Description, EmptyAPI, Fragment,
74+ FramingRender (..), FramingUnrender (..), FromSourceIO (..),
75+ Header', If, IsSecure (..), NoContentVerb, QueryFlag,
76+ QueryParam', QueryParams, Raw, ReflectMethod (reflectMethod),
77+ RemoteHost, ReqBody', SBool (..), SBoolI (..), SourceIO,
78+ Stream, StreamBody', Summary, ToSourceIO (..), Vault, Verb,
79+ WithNamedContext, NamedRoutes)
80+import Servant.API.Generic (GenericMode(..), ToServant, ToServantApi, GServantProduct, toServant, fromServant)
8081import Servant.API.ContentTypes
8182 (AcceptHeader (..), AllCTRender (..), AllCTUnrender (..),
82− AllMime, MimeRender (..), MimeUnrender (..), canHandleAcceptH,
83− NoContent)
83+ AllMime, MimeRender (..), MimeUnrender (..), NoContent,
84+ canHandleAcceptH)
8485import Servant.API.Modifiers
8586 (FoldLenient, FoldRequired, RequestArgument,
8687 unfoldRequestArgument)
8788import Servant.API.ResponseHeaders
8889 (GetHeaders, Headers, getHeaders, getResponse)
90+import Servant.API.Status
91+ (statusFromNat)
8992import qualified Servant.Types.SourceT as S
93+import Servant.API.TypeErrors
9094import Web.HttpApiData
91− (FromHttpApiData, parseHeader, parseQueryParam,
92− parseUrlPieces, parseUrlPiece)
95+ (FromHttpApiData, parseHeader, parseQueryParam, parseUrlPiece,
96+ parseUrlPieces)
9397
9498import Servant.Server.Internal.BasicAuth
9599import Servant.Server.Internal.Context
96100import Servant.Server.Internal.Delayed
97101import Servant.Server.Internal.DelayedIO
102+import Servant.Server.Internal.ErrorFormatter
98103import Servant.Server.Internal.Handler
99104import Servant.Server.Internal.Router
100105import Servant.Server.Internal.RouteResult
101106import Servant.Server.Internal.RoutingApplication
102107import Servant.Server.Internal.ServerError
103108
104−#ifdef HAS_TYPE_ERROR
105109import GHC.TypeLits
106110 (ErrorMessage (..), TypeError)
107−#endif
111+import Servant.API.TypeLevel
112+ (AtLeastOneFragment, FragmentUnique)
108113
109114class HasServer api context where
110115 type ServerT api (m :: * -> *) :: *
@@ -168,7 +173,10 @@ instance (HasServer a context, HasServer b context) => HasServer (a :<|> b) cont
168173-- > server = getBook
169174-- > where getBook :: Text -> Handler Book
170175-- > getBook isbn = ...
171−instance (KnownSymbol capture, FromHttpApiData a, HasServer api context, SBoolI (FoldLenient mods))
176+instance (KnownSymbol capture, FromHttpApiData a, Typeable a
177+ , HasServer api context, SBoolI (FoldLenient mods)
178+ , HasContextEntry (MkContextWithErrorFormatter context) ErrorFormatters
179+ )
172180 => HasServer (Capture' mods capture a :> api) context where
173181
174182 type ServerT (Capture' mods capture a :> api) m =
@@ -177,15 +185,19 @@ instance (KnownSymbol capture, FromHttpApiData a, HasServer api context, SBoolI
177185 hoistServerWithContext _ pc nt s = hoistServerWithContext (Proxy :: Proxy api) pc nt . s
178186
179187 route Proxy context d =
180− CaptureRouter $
188+ CaptureRouter [hint] $
181189 route (Proxy :: Proxy api)
182190 context
183− (addCapture d $ \ txt -> case ( sbool :: SBool (FoldLenient mods)
184− , parseUrlPiece txt :: Either T.Text a) of
185− (SFalse, Left e) -> delayedFail err400 { errBody = cs e }
186− (SFalse, Right v) -> return v
187− (STrue, piece) -> return $ (either (Left . cs) Right) piece
188− )
191+ (addCapture d $ \ txt -> withRequest $ \ request ->
192+ case ( sbool :: SBool (FoldLenient mods)
193+ , parseUrlPiece txt :: Either T.Text a) of
194+ (SFalse, Left e) -> delayedFail $ formatError rep request $ cs e
195+ (SFalse, Right v) -> return v
196+ (STrue, piece) -> return $ (either (Left . cs) Right) piece)
197+ where
198+ rep = typeRep (Proxy :: Proxy Capture')
199+ formatError = urlParseErrorFormatter $ getContextEntry (mkContextWithErrorFormatter context)
200+ hint = CaptureHint (T.pack $ symbolVal $ Proxy @capture) (typeRep (Proxy :: Proxy a))
189201
190202-- | If you use 'CaptureAll' in one of the endpoints for your API,
191203-- this automatically requires your server-side handler to be a
@@ -204,7 +216,10 @@ instance (KnownSymbol capture, FromHttpApiData a, HasServer api context, SBoolI
204216-- > server = getSourceFile
205217-- > where getSourceFile :: [Text] -> Handler Book
206218-- > getSourceFile pathSegments = ...
207−instance (KnownSymbol capture, FromHttpApiData a, HasServer api context)
219+instance (KnownSymbol capture, FromHttpApiData a, Typeable a
220+ , HasServer api context
221+ , HasContextEntry (MkContextWithErrorFormatter context) ErrorFormatters
222+ )
208223 => HasServer (CaptureAll capture a :> api) context where
209224
210225 type ServerT (CaptureAll capture a :> api) m =
@@ -213,14 +228,18 @@ instance (KnownSymbol capture, FromHttpApiData a, HasServer api context)
213228 hoistServerWithContext _ pc nt s = hoistServerWithContext (Proxy :: Proxy api) pc nt . s
214229
215230 route Proxy context d =
216− CaptureAllRouter $
231+ CaptureAllRouter [hint] $
217232 route (Proxy :: Proxy api)
218233 context
219− (addCapture d $ \ txts -> case parseUrlPieces txts of
220− Left _ -> delayedFail err400
221− Right v -> return v
234+ (addCapture d $ \ txts -> withRequest $ \ request ->
235+ case parseUrlPieces txts of
236+ Left e -> delayedFail $ formatError rep request $ cs e
237+ Right v -> return v
222238 )
223−
239+ where
240+ rep = typeRep (Proxy :: Proxy CaptureAll)
241+ formatError = urlParseErrorFormatter $ getContextEntry (mkContextWithErrorFormatter context)
242+ hint = CaptureHint (T.pack $ symbolVal $ Proxy @capture) (typeRep (Proxy :: Proxy [a]))
224243
225244allowedMethodHead :: Method -> Request -> Bool
226245allowedMethodHead method request = method == methodGet && requestMethod request == methodHead
@@ -240,10 +259,10 @@ methodCheck method request
240259-- body check is no longer an option. However, we now run the accept
241260-- check before the body check and can therefore afford to make it
242261-- recoverable.
243−acceptCheck :: (AllMime list) => Proxy list -> B.ByteString -> DelayedIO ()
262+acceptCheck :: (AllMime list) => Proxy list -> AcceptHeader -> DelayedIO ()
244263acceptCheck proxy accH
245− | canHandleAcceptH proxy (AcceptHeader accH) = return ()
246− | otherwise = delayedFail err406
264+ | canHandleAcceptH proxy accH = return ()
265+ | otherwise = delayedFail err406
247266
248267methodRouter :: (AllCTRender ctypes a)
249268 => (b -> ([(HeaderName, B.ByteString)], a))
@@ -253,12 +272,12 @@ methodRouter :: (AllCTRender ctypes a)
253272methodRouter splitHeaders method proxy status action = leafRouter route'
254273 where
255274 route' env request respond =
256− let accH = fromMaybe ct_wildcard $ lookup hAccept $ requestHeaders request
275+ let accH = getAcceptHeader request
257276 in runAction (action `addMethodCheck` methodCheck method request
258277 `addAcceptCheck` acceptCheck proxy accH
259278 ) env request respond $ \ output -> do
260279 let (headers, b) = splitHeaders output
261− case handleAcceptH proxy (AcceptHeader accH) b of
280+ case handleAcceptH proxy accH b of
262281 Nothing -> FailFatal err406 -- this should not happen (checked before), so we make it fatal if it does
263282 Just (contentT, body) ->
264283 let bdy = if allowedMethodHead method request then "" else body
@@ -284,7 +303,7 @@ instance {-# OVERLAPPABLE #-}
284303
285304 route Proxy _ = methodRouter ([],) method (Proxy :: Proxy ctypes) status
286305 where method = reflectMethod (Proxy :: Proxy method)
287− status = toEnum . fromInteger $ natVal (Proxy :: Proxy status)
306+ status = statusFromNat (Proxy :: Proxy status)
288307
289308instance {-# OVERLAPPING #-}
290309 ( AllCTRender ctypes a, ReflectMethod method, KnownNat status
@@ -296,7 +315,7 @@ instance {-# OVERLAPPING #-}
296315
297316 route Proxy _ = methodRouter (\x -> (getHeaders x, getResponse x)) method (Proxy :: Proxy ctypes) status
298317 where method = reflectMethod (Proxy :: Proxy method)
299− status = toEnum . fromInteger $ natVal (Proxy :: Proxy status)
318+ status = statusFromNat (Proxy :: Proxy status)
300319
301320instance (ReflectMethod method) =>
302321 HasServer (NoContentVerb method) context where
@@ -317,7 +336,7 @@ instance {-# OVERLAPPABLE #-}
317336
318337 route Proxy _ = streamRouter ([],) method status (Proxy :: Proxy framing) (Proxy :: Proxy ctype)
319338 where method = reflectMethod (Proxy :: Proxy method)
320− status = toEnum . fromInteger $ natVal (Proxy :: Proxy status)
339+ status = statusFromNat (Proxy :: Proxy status)
321340
322341
323342instance {-# OVERLAPPING #-}
@@ -331,7 +350,7 @@ instance {-# OVERLAPPING #-}
331350
332351 route Proxy _ = streamRouter (\x -> (getHeaders x, getResponse x)) method status (Proxy :: Proxy framing) (Proxy :: Proxy ctype)
333352 where method = reflectMethod (Proxy :: Proxy method)
334− status = toEnum . fromInteger $ natVal (Proxy :: Proxy status)
353+ status = statusFromNat (Proxy :: Proxy status)
335354
336355
337356streamRouter :: forall ctype a c chunk env framing. (MimeRender ctype chunk, FramingRender framing, ToSourceIO chunk a) =>
@@ -343,7 +362,7 @@ streamRouter :: forall ctype a c chunk env framing. (MimeRender ctype chunk, Fra
343362 -> Delayed env (Handler c)
344363 -> Router env
345364streamRouter splitHeaders method status framingproxy ctypeproxy action = leafRouter $ \env request respond ->
346− let accH = fromMaybe ct_wildcard $ lookup hAccept $ requestHeaders request
365+ let AcceptHeader accH = getAcceptHeader request
347366 cmediatype = NHM.matchAccept [contentType ctypeproxy] accH
348367 accCheck = when (isNothing cmediatype) $ delayedFail err406
349368 contentHeader = (hContentType, NHM.renderHeader . maybeToList $ cmediatype)
@@ -388,6 +407,7 @@ streamRouter splitHeaders method status framingproxy ctypeproxy action = leafRou
388407instance
389408 (KnownSymbol sym, FromHttpApiData a, HasServer api context
390409 , SBoolI (FoldRequired mods), SBoolI (FoldLenient mods)
410+ , HasContextEntry (MkContextWithErrorFormatter context) ErrorFormatters
391411 )
392412 => HasServer (Header' mods sym a :> api) context where
393413------
@@ -399,6 +419,9 @@ instance
399419 route Proxy context subserver = route (Proxy :: Proxy api) context $
400420 subserver `addHeaderCheck` withRequest headerCheck
401421 where
422+ rep = typeRep (Proxy :: Proxy Header')
423+ formatError = headerParseErrorFormatter $ getContextEntry (mkContextWithErrorFormatter context)
424+
402425 headerName :: IsString n => n
403426 headerName = fromString $ symbolVal (Proxy :: Proxy sym)
404427
@@ -409,15 +432,13 @@ instance
409432 mev :: Maybe (Either T.Text a)
410433 mev = fmap parseHeader $ lookup headerName (requestHeaders req)
411434
412− errReq = delayedFailFatal err400
413− { errBody = "Header " <> headerName <> " is required"
414− }
435+ errReq = delayedFailFatal $ formatError rep req
436+ $ "Header " <> headerName <> " is required"
415437
416− errSt e = delayedFailFatal err400
417− { errBody = cs $ "Error parsing header "
418− <> headerName
419− <> " failed: " <> e
420− }
438+ errSt e = delayedFailFatal $ formatError rep req
439+ $ cs $ "Error parsing header "
440+ <> headerName
441+ <> " failed: " <> e
421442
422443-- | If you use @'QueryParam' "author" Text@ in one of the endpoints for your API,
423444-- this automatically requires your server-side handler to be a function
@@ -443,6 +464,7 @@ instance
443464instance
444465 ( KnownSymbol sym, FromHttpApiData a, HasServer api context
445466 , SBoolI (FoldRequired mods), SBoolI (FoldLenient mods)
467+ , HasContextEntry (MkContextWithErrorFormatter context) ErrorFormatters
446468 )
447469 => HasServer (QueryParam' mods sym a :> api) context where
448470------
@@ -455,6 +477,9 @@ instance
455477 let querytext = queryToQueryText . queryString
456478 paramname = cs $ symbolVal (Proxy :: Proxy sym)
457479
480+ rep = typeRep (Proxy :: Proxy QueryParam')
481+ formatError = urlParseErrorFormatter $ getContextEntry (mkContextWithErrorFormatter context)
482+
458483 parseParam :: Request -> DelayedIO (RequestArgument mods a)
459484 parseParam req =
460485 unfoldRequestArgument (Proxy :: Proxy mods) errReq errSt mev
@@ -462,14 +487,12 @@ instance
462487 mev :: Maybe (Either T.Text a)
463488 mev = fmap parseQueryParam $ join $ lookup paramname $ querytext req
464489
465− errReq = delayedFailFatal err400
466− { errBody = cs $ "Query parameter " <> paramname <> " is required"
467− }
490+ errReq = delayedFailFatal $ formatError rep req
491+ $ cs $ "Query parameter " <> paramname <> " is required"
468492
469− errSt e = delayedFailFatal err400
470− { errBody = cs $ "Error parsing query parameter "
471− <> paramname <> " failed: " <> e
472− }
493+ errSt e = delayedFailFatal $ formatError rep req
494+ $ cs $ "Error parsing query parameter "
495+ <> paramname <> " failed: " <> e
473496
474497 delayed = addParameterCheck subserver . withRequest $ \req ->
475498 parseParam req
@@ -495,7 +518,8 @@ instance
495518-- > server = getBooksBy
496519-- > where getBooksBy :: [Text] -> Handler [Book]
497520-- > getBooksBy authors = ...return all books by these authors...
498−instance (KnownSymbol sym, FromHttpApiData a, HasServer api context)
521+instance (KnownSymbol sym, FromHttpApiData a, HasServer api context
522+ , HasContextEntry (MkContextWithErrorFormatter context) ErrorFormatters)
499523 => HasServer (QueryParams sym a :> api) context where
500524
501525 type ServerT (QueryParams sym a :> api) m =
@@ -506,21 +530,23 @@ instance (KnownSymbol sym, FromHttpApiData a, HasServer api context)
506530 route Proxy context subserver = route (Proxy :: Proxy api) context $
507531 subserver `addParameterCheck` withRequest paramsCheck
508532 where
533+ rep = typeRep (Proxy :: Proxy QueryParams)
534+ formatError = urlParseErrorFormatter $ getContextEntry (mkContextWithErrorFormatter context)
535+
509536 paramname = cs $ symbolVal (Proxy :: Proxy sym)
510537 paramsCheck req =
511538 case partitionEithers $ fmap parseQueryParam params of
512539 ([], parsed) -> return parsed
513− (errs, _) -> delayedFailFatal err400
514− { errBody = cs $ "Error parsing query parameter(s) "
515− <> paramname <> " failed: "
516− <> T.intercalate ", " errs
517− }
540+ (errs, _) -> delayedFailFatal $ formatError rep req
541+ $ cs $ "Error parsing query parameter(s) "
542+ <> paramname <> " failed: "
543+ <> T.intercalate ", " errs
518544 where
519545 params :: [T.Text]
520546 params = mapMaybe snd
521547 . filter (looksLikeParam . fst)
522− . queryToQueryText
523− . queryString
548+ . queryToQueryText
549+ . queryString
524550 $ req
525551
526552 looksLikeParam name = name == paramname || name == (paramname <> "[]")
@@ -588,7 +614,7 @@ instance HasServer Raw context where
588614-- The @Content-Type@ header is inspected, and the list provided is used to
589615-- attempt deserialization. If the request does not have a @Content-Type@
590616-- header, it is treated as @application/octet-stream@ (as specified in
591−-- <http://tools.ietf.org/html/rfc7231#section-3.1.1.5 RFC7231>.
617+-- [RFC 7231 section 3.1.1.5](http://tools.ietf.org/html/rfc7231#section-3.1.1.5)).
592618-- This lets servant worry about extracting it from the request and turning
593619-- it into a value of the type you specify.
594620--
@@ -604,6 +630,7 @@ instance HasServer Raw context where
604630-- > where postBook :: Book -> Handler Book
605631-- > postBook book = ...insert into your db...
606632instance ( AllCTUnrender list a, HasServer api context, SBoolI (FoldLenient mods)
633+ , HasContextEntry (MkContextWithErrorFormatter context) ErrorFormatters
607634 ) => HasServer (ReqBody' mods list a :> api) context where
608635
609636 type ServerT (ReqBody' mods list a :> api) m =
@@ -615,6 +642,9 @@ instance ( AllCTUnrender list a, HasServer api context, SBoolI (FoldLenient mods
615642 = route (Proxy :: Proxy api) context $
616643 addBodyCheck subserver ctCheck bodyCheck
617644 where
645+ rep = typeRep (Proxy :: Proxy ReqBody')
646+ formatError = bodyParserErrorFormatter $ getContextEntry (mkContextWithErrorFormatter context)
647+
618648 -- Content-Type check, we only lookup we can try to parse the request body
619649 ctCheck = withRequest $ \ request -> do
620650 -- See HTTP RFC 2616, section 7.2.1
@@ -633,7 +663,7 @@ instance ( AllCTUnrender list a, HasServer api context, SBoolI (FoldLenient mods
633663 case sbool :: SBool (FoldLenient mods) of
634664 STrue -> return mrqbody
635665 SFalse -> case mrqbody of
636− Left e -> delayedFailFatal err400 { errBody = cs e }
666+ Left e -> delayedFailFatal $ formatError rep request e
637667 Right v -> return v
638668
639669instance
@@ -656,7 +686,7 @@ instance
656686 bodyCheck fromRS = withRequest $ \req -> do
657687 let mimeUnrender' = mimeUnrender (Proxy :: Proxy ctype) :: BL.ByteString -> Either String chunk
658688 let framingUnrender' = framingUnrender (Proxy :: Proxy framing) mimeUnrender' :: SourceIO B.ByteString -> SourceIO chunk
659− let body = requestBody req
689+ let body = getRequestBodyChunk req
660690 let rs = S.fromAction B.null body
661691 let rs' = fromRS $ framingUnrender' rs
662692 return rs'
@@ -725,12 +755,12 @@ data EmptyServer = EmptyServer deriving (Typeable, Eq, Show, Bounded, Enum)
725755emptyServer :: ServerT EmptyAPI m
726756emptyServer = Tagged EmptyServer
727757
728−-- | The server for an `EmptyAPI` is `emptyAPIServer`.
758+-- | The server for an `EmptyAPI` is `emptyServer`.
729759--
730760-- > type MyApi = "nothing" :> EmptyApi
731761-- >
732762-- > server :: Server MyApi
733−-- > server = emptyAPIServer
763+-- > server = emptyServer
734764instance HasServer EmptyAPI context where
735765 type ServerT EmptyAPI m = Tagged m EmptyServer
736766
@@ -759,7 +789,10 @@ instance ( KnownSymbol realm
759789-- * helpers
760790
761791ct_wildcard :: B.ByteString
762−ct_wildcard = "*" <> "/" <> "*" -- Because CPP
792+ct_wildcard = "*" <> "/" <> "*"
793+
794+getAcceptHeader :: Request -> AcceptHeader
795+getAcceptHeader = AcceptHeader . fromMaybe ct_wildcard . lookup hAccept . requestHeaders
763796
764797-- * General Authentication
765798
@@ -784,39 +817,15 @@ instance (HasContextEntry context (NamedContext name subContext), HasServer subA
784817 hoistServerWithContext _ _ nt s = hoistServerWithContext (Proxy :: Proxy subApi) (Proxy :: Proxy subContext) nt s
785818
786819-------------------------------------------------------------------------------
787−-- TypeError helpers
820+-- Custom type errors
788821-------------------------------------------------------------------------------
789822
790−#ifdef HAS_TYPE_ERROR
791−-- | This instance catches mistakes when there are non-saturated
792−-- type applications on LHS of ':>'.
793−--
794−-- >>> serve (Proxy :: Proxy (Capture "foo" :> Get '[JSON] Int)) (error "...")
795−-- ...
796−-- ...Expected something of kind Symbol or *, got: k -> l on the LHS of ':>'.
797−-- ...Maybe you haven't applied enough arguments to
798−-- ...Capture' '[] "foo"
799−-- ...
800−--
801−-- >>> undefined :: Server (Capture "foo" :> Get '[JSON] Int)
802−-- ...
803−-- ...Expected something of kind Symbol or *, got: k -> l on the LHS of ':>'.
804−-- ...Maybe you haven't applied enough arguments to
805−-- ...Capture' '[] "foo"
806−-- ...
807−--
808−instance TypeError (HasServerArrowKindError arr) => HasServer ((arr :: k -> l) :> api) context
823+-- Erroring instance for 'HasServer' when a combinator is not fully applied
824+instance TypeError (PartialApplication HasServer arr) => HasServer ((arr :: a -> b) :> sub) context
809825 where
810− type ServerT (arr :> api) m = TypeError (HasServerArrowKindError arr)
811− -- it doens't really matter what sub route we peak
812− route _ _ _ = error "servant-server panic: impossible happened in HasServer (arr :> api)"
813− hoistServerWithContext _ _ _ = id
814−
815−-- Cannot have TypeError here, otherwise use of this symbol will error :)
816−type HasServerArrowKindError arr =
817− 'Text "Expected something of kind Symbol or *, got: k -> l on the LHS of ':>'."
818− ':$$: 'Text "Maybe you haven't applied enough arguments to"
819− ':$$: 'ShowType arr
826+ type ServerT (arr :> sub) _ = TypeError (PartialApplication (HasServer :: * -> [*] -> Constraint) arr)
827+ route = error "unreachable"
828+ hoistServerWithContext _ _ _ _ = error "unreachable"
820829
821830-- | This instance prevents from accidentally using '->' instead of ':>'
822831--
@@ -850,7 +859,103 @@ type HasServerArrowTypeError a b =
850859 ':$$: 'ShowType a
851860 ':$$: 'Text "and"
852861 ':$$: 'ShowType b
853−#endif
862+
863+-- Erroring instances for 'HasServer' for unknown API combinators
864+
865+-- XXX: This omits the @context@ parameter, e.g.:
866+--
867+-- "There is no instance for HasServer (Bool :> …)". Do we care ?
868+instance {-# OVERLAPPABLE #-} TypeError (NoInstanceForSub HasServer ty) => HasServer (ty :> sub) context
869+
870+instance {-# OVERLAPPABLE #-} TypeError (NoInstanceFor (HasServer api context)) => HasServer api context
871+
872+-- | Ignore @'Fragment'@ in server handlers.
873+-- See <https://ietf.org/rfc/rfc2616.html#section-15.1.3> for more details.
874+--
875+-- Example:
876+--
877+-- > type MyApi = "books" :> Fragment Text :> Get '[JSON] [Book]
878+-- >
879+-- > server :: Server MyApi
880+-- > server = getBooks
881+-- > where getBooks :: Handler [Book]
882+-- > getBooks = ...return all books...
883+instance (AtLeastOneFragment api, FragmentUnique (Fragment a1 :> api), HasServer api context)
884+ => HasServer (Fragment a1 :> api) context where
885+ type ServerT (Fragment a1 :> api) m = ServerT api m
886+
887+ route _ = route (Proxy :: Proxy api)
888+
889+ hoistServerWithContext _ = hoistServerWithContext (Proxy :: Proxy api)
854890
855891-- $setup
856892-- >>> import Servant
893+
894+-- | A type that specifies that an API record contains a server implementation.
895+data AsServerT (m :: * -> *)
896+instance GenericMode (AsServerT m) where
897+ type AsServerT m :- api = ServerT api m
898+
899+type AsServer = AsServerT Handler
900+
901+
902+-- | Set of constraints required to convert to / from vanilla server types.
903+type GServerConstraints api m =
904+ ( ToServant api (AsServerT m) ~ ServerT (ToServantApi api) m
905+ , GServantProduct (Rep (api (AsServerT m)))
906+ )
907+
908+-- | This class is a necessary evil: in the implementation of 'HasServer' for
909+-- @'NamedRoutes' api@, we essentially need the quantified constraint @forall
910+-- m. 'GServerConstraints' m@ to hold.
911+--
912+-- We cannot require do that directly as the definition of 'GServerConstraints'
913+-- contains type family applications ('Rep' and 'ServerT'). The trick is to hide
914+-- those type family applications behind a typeclass providing evidence for
915+-- @'GServerConstraints' api m@ in the form of a dictionary, and require that
916+-- @forall m. 'GServer' api m@ instead.
917+--
918+-- Users shouldn't have to worry about this class, as the only possible instance
919+-- is provided in this module for all record APIs.
920+
921+class GServer (api :: * -> *) (m :: * -> *) where
922+ gServerProof :: Dict (GServerConstraints api m)
923+
924+instance
925+ ( ToServant api (AsServerT m) ~ ServerT (ToServantApi api) m
926+ , GServantProduct (Rep (api (AsServerT m)))
927+ ) => GServer api m where
928+ gServerProof = Dict
929+
930+instance
931+ ( HasServer (ToServantApi api) context
932+ , forall m. Generic (api (AsServerT m))
933+ , forall m. GServer api m
934+ ) => HasServer (NamedRoutes api) context where
935+
936+ type ServerT (NamedRoutes api) m = api (AsServerT m)
937+
938+ route
939+ :: Proxy (NamedRoutes api)
940+ -> Context context
941+ -> Delayed env (api (AsServerT Handler))
942+ -> Router env
943+ route _ ctx delayed =
944+ case gServerProof @api @Handler of
945+ Dict -> route (Proxy @(ToServantApi api)) ctx (toServant <$> delayed)
946+
947+ hoistServerWithContext
948+ :: forall m n. Proxy (NamedRoutes api)
949+ -> Proxy context
950+ -> (forall x. m x -> n x)
951+ -> api (AsServerT m)
952+ -> api (AsServerT n)
953+ hoistServerWithContext _ pctx nat server =
954+ case (gServerProof @api @m, gServerProof @api @n) of
955+ (Dict, Dict) ->
956+ fromServant servantSrvN
957+ where
958+ servantSrvM :: ServerT (ToServantApi api) m =
959+ toServant server
960+ servantSrvN :: ServerT (ToServantApi api) n =
961+ hoistServerWithContext (Proxy @(ToServantApi api)) pctx nat servantSrvM