Move erroring instances of HasServer to separate file

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Nicolas BACQUEY 2022-03-17 17:10:05 +01:00
parent 4a04825044
commit b7625a8039
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4 changed files with 105 additions and 66 deletions

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@ -53,6 +53,9 @@ library
Servant.Server.StaticFiles
Servant.Server.UVerb
other-modules:
Servant.Server.TypeErrors
-- deprecated
exposed-modules:
Servant.Utils.StaticFiles

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@ -126,6 +126,7 @@ import Data.Text
import Network.Wai
(Application)
import Servant.Server.Internal
import Servant.Server.TypeErrors ()
import Servant.Server.UVerb

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@ -42,7 +42,7 @@ import qualified Data.ByteString as B
import qualified Data.ByteString.Builder as BB
import qualified Data.ByteString.Char8 as BC8
import qualified Data.ByteString.Lazy as BL
import Data.Constraint (Constraint, Dict(..))
import Data.Constraint (Dict(..))
import Data.Either
(partitionEithers)
import Data.Maybe
@ -57,7 +57,7 @@ import qualified Data.Text as T
import Data.Typeable
import GHC.Generics
import GHC.TypeLits
(KnownNat, KnownSymbol, TypeError, symbolVal)
(KnownNat, KnownSymbol, symbolVal)
import qualified Network.HTTP.Media as NHM
import Network.HTTP.Types hiding
(Header, ResponseHeaders)
@ -91,7 +91,6 @@ import Servant.API.ResponseHeaders
import Servant.API.Status
(statusFromNat)
import qualified Servant.Types.SourceT as S
import Servant.API.TypeErrors
import Web.HttpApiData
(FromHttpApiData, parseHeader, parseQueryParam, parseUrlPiece,
parseUrlPieces)
@ -107,8 +106,6 @@ import Servant.Server.Internal.RouteResult
import Servant.Server.Internal.RoutingApplication
import Servant.Server.Internal.ServerError
import GHC.TypeLits
(ErrorMessage (..))
import Servant.API.TypeLevel
(AtLeastOneFragment, FragmentUnique)
@ -817,67 +814,6 @@ instance (HasContextEntry context (NamedContext name subContext), HasServer subA
hoistServerWithContext _ _ nt s = hoistServerWithContext (Proxy :: Proxy subApi) (Proxy :: Proxy subContext) nt s
-------------------------------------------------------------------------------
-- Custom type errors
-------------------------------------------------------------------------------
-- Erroring instance for 'HasServer' when a combinator is not fully applied
instance TypeError (PartialApplication
#if __GLASGOW_HASKELL__ >= 904
@(Type -> [Type] -> Constraint)
#endif
HasServer arr) => HasServer ((arr :: a -> b) :> sub) context
where
type ServerT (arr :> sub) _ = TypeError (PartialApplication (HasServer :: * -> [*] -> Constraint) arr)
route = error "unreachable"
hoistServerWithContext _ _ _ _ = error "unreachable"
-- | This instance prevents from accidentally using '->' instead of ':>'
--
-- >>> serve (Proxy :: Proxy (Capture "foo" Int -> Get '[JSON] Int)) (error "...")
-- ...
-- ...No instance HasServer (a -> b).
-- ...Maybe you have used '->' instead of ':>' between
-- ...Capture' '[] "foo" Int
-- ...and
-- ...Verb 'GET 200 '[JSON] Int
-- ...
--
-- >>> undefined :: Server (Capture "foo" Int -> Get '[JSON] Int)
-- ...
-- ...No instance HasServer (a -> b).
-- ...Maybe you have used '->' instead of ':>' between
-- ...Capture' '[] "foo" Int
-- ...and
-- ...Verb 'GET 200 '[JSON] Int
-- ...
--
instance TypeError (HasServerArrowTypeError a b) => HasServer (a -> b) context
where
type ServerT (a -> b) m = TypeError (HasServerArrowTypeError a b)
route _ _ _ = error "servant-server panic: impossible happened in HasServer (a -> b)"
hoistServerWithContext _ _ _ = id
type HasServerArrowTypeError a b =
'Text "No instance HasServer (a -> b)."
':$$: 'Text "Maybe you have used '->' instead of ':>' between "
':$$: 'ShowType a
':$$: 'Text "and"
':$$: 'ShowType b
-- Erroring instances for 'HasServer' for unknown API combinators
-- XXX: This omits the @context@ parameter, e.g.:
--
-- "There is no instance for HasServer (Bool :> …)". Do we care ?
instance {-# OVERLAPPABLE #-} TypeError (NoInstanceForSub
#if __GLASGOW_HASKELL__ >= 904
@(Type -> [Type] -> Constraint)
#endif
HasServer ty) => HasServer (ty :> sub) context
instance {-# OVERLAPPABLE #-} TypeError (NoInstanceFor (HasServer api context)) => HasServer api context
-- | Ignore @'Fragment'@ in server handlers.
-- See <https://ietf.org/rfc/rfc2616.html#section-15.1.3> for more details.
--

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@ -0,0 +1,99 @@
{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE UndecidableInstances #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
{-# OPTIONS_GHC -fno-warn-missing-methods #-}
#if __GLASGOW_HASKELL__ >= 904
{-# LANGUAGE TypeApplications #-}
#endif
-- | This module contains erroring instances for @Servant.Server.Internal@.
-- They are separated from the bulk of the code, because they raise "missing methods"
-- warnings. These warnings are expected, but ignoring them would lead to missing
-- relevant warnings in @SServant.Server.Internal@. Therefore, we put them in a separate
-- file, and ignore the warnings here.
module Servant.Server.TypeErrors ()
where
import Data.Constraint (Constraint)
import GHC.TypeLits
(TypeError)
import Prelude ()
import Prelude.Compat
import Servant.API
((:>))
import Servant.API.TypeErrors
import Servant.Server.Internal
import GHC.TypeLits
(ErrorMessage (..))
#if __GLASGOW_HASKELL__ >= 904
import Data.Kind (Type)
#endif
-- Erroring instance for 'HasServer' when a combinator is not fully applied
instance TypeError (PartialApplication
#if __GLASGOW_HASKELL__ >= 904
@(Type -> [Type] -> Constraint)
#endif
HasServer arr) => HasServer ((arr :: a -> b) :> sub) context
where
type ServerT (arr :> sub) _ = TypeError (PartialApplication (HasServer :: * -> [*] -> Constraint) arr)
route = error "unreachable"
hoistServerWithContext _ _ _ _ = error "unreachable"
-- | This instance prevents from accidentally using '->' instead of ':>'
--
-- >>> serve (Proxy :: Proxy (Capture "foo" Int -> Get '[JSON] Int)) (error "...")
-- ...
-- ...No instance HasServer (a -> b).
-- ...Maybe you have used '->' instead of ':>' between
-- ...Capture' '[] "foo" Int
-- ...and
-- ...Verb 'GET 200 '[JSON] Int
-- ...
--
-- >>> undefined :: Server (Capture "foo" Int -> Get '[JSON] Int)
-- ...
-- ...No instance HasServer (a -> b).
-- ...Maybe you have used '->' instead of ':>' between
-- ...Capture' '[] "foo" Int
-- ...and
-- ...Verb 'GET 200 '[JSON] Int
-- ...
--
instance TypeError (HasServerArrowTypeError a b) => HasServer (a -> b) context
where
type ServerT (a -> b) m = TypeError (HasServerArrowTypeError a b)
route _ _ _ = error "servant-server panic: impossible happened in HasServer (a -> b)"
hoistServerWithContext _ _ _ = id
type HasServerArrowTypeError a b =
'Text "No instance HasServer (a -> b)."
':$$: 'Text "Maybe you have used '->' instead of ':>' between "
':$$: 'ShowType a
':$$: 'Text "and"
':$$: 'ShowType b
-- Erroring instances for 'HasServer' for unknown API combinators
-- XXX: This omits the @context@ parameter, e.g.:
--
-- "There is no instance for HasServer (Bool :> …)". Do we care ?
instance {-# OVERLAPPABLE #-} TypeError (NoInstanceForSub
#if __GLASGOW_HASKELL__ >= 904
@(Type -> [Type] -> Constraint)
#endif
HasServer ty) => HasServer (ty :> sub) context
instance {-# OVERLAPPABLE #-} TypeError (NoInstanceFor (HasServer api context)) => HasServer api context