d004805 · servant · git.iko.soy

servant-server/src/Servant/Server.hs+3−2

compare with master

unifiedsplit

@@ -207,7 +207,7 @@ layoutWithContext p context =

207-- monad. Or have your types ensure that your handlers don't do any IO. Enter

208-- `enter`.

209--

210−-- With `enter`, you can provide a function, wrapped in the `(:~>)` / `Nat`

210+-- With `enter`, you can provide a function, wrapped in the `(:~>)` / `NT`

211-- newtype, to convert any number of endpoints from one type constructor to

212-- another. For example

213--

@@ -215,7 +215,8 @@ layoutWithContext p context =

215-- >>> import qualified Control.Category as C

216-- >>> type ReaderAPI = "ep1" :> Get '[JSON] Int :<|> "ep2" :> Get '[JSON] String

217-- >>> let readerServer = return 1797 :<|> ask :: ServerT ReaderAPI (Reader String)

218−-- >>> let mainServer = enter (generalizeNat C.. (runReaderTNat "hi")) readerServer :: Server ReaderAPI

218+-- >>> let nt = generalizeNat C.. (runReaderTNat "hi") :: Reader String :~> Handler

219+-- >>> let mainServer = enter nt readerServer :: Server ReaderAPI

219--

220--

220

221

221-- $setup

222-- $setup

servant-server/test/Servant/ArbitraryMonadServerSpec.hs+2−1

@@ -5,6 +5,7 @@ module Servant.ArbitraryMonadServerSpec where

5

6import qualified Control.Category as C

7import Control.Monad.Reader

8+import Data.Functor.Identity

8import Data.Proxy

9import Data.Proxy

9import Servant.API

10import Servant.API

10import Servant.Server

11import Servant.Server

@@ -40,7 +41,7 @@ readerServer :: Server ReaderAPI

40readerServer = enter fReader readerServer'

41readerServer = enter fReader readerServer'

41

42

42combinedReaderServer' :: ServerT CombinedAPI (Reader String)

43combinedReaderServer' :: ServerT CombinedAPI (Reader String)

43−combinedReaderServer' = readerServer' :<|> enter generalizeNat (return True)

44+combinedReaderServer' = readerServer' :<|> enter (generalizeNat :: Identity :~> Reader String) (return True)

44

45

45combinedReaderServer :: Server CombinedAPI

46combinedReaderServer :: Server CombinedAPI

46combinedReaderServer = enter fReader combinedReaderServer'

47combinedReaderServer = enter fReader combinedReaderServer'

servant/src/Servant/Utils/Enter.hs+27−7

@@ -27,21 +27,41 @@ import Prelude.Compat

27

28import Servant.API

29

30−class Enter typ arg ret | typ arg -> ret, typ ret -> arg where

30+type family Entered m n api where

31+ Entered m n (m a) = n a

32+ Entered m n (a -> api) = a -> Entered m n api

33+ Entered m n (api1 :<|> api2) = Entered m n api1 :<|> Entered m n api2

34+

35+class ( Entered m n typ ~ ret

36+ , Entered n m ret ~ typ

37+ )

38+ => Enter typ m n ret

39+ where

31− enter :: arg -> typ -> ret

40+ enter :: (m :~> n) -> typ -> ret

32

41

33-- ** Servant combinators

42-- ** Servant combinators

43+

44+instance

45+ ( Entered m1 n1 (typ1 :<|> typ2) ~ (ret1 :<|> ret2)

46+ , Entered n1 m1 (ret1 :<|> ret2) ~ (typ1 :<|> typ2)

34−instance ( Enter typ1 arg1 ret1, Enter typ2 arg2 ret2

47+ , Enter typ1 m1 n1 ret1, Enter typ2 m2 n2 ret2

35− , arg1 ~ arg2

48+ , m1 ~ m2, n1 ~ n2

36− ) => Enter (typ1 :<|> typ2) arg1 (ret1 :<|> ret2) where

49+ ) => Enter (typ1 :<|> typ2) m1 n1 (ret1 :<|> ret2)

50+ where

37 enter e (a :<|> b) = enter e a :<|> enter e b

51 enter e (a :<|> b) = enter e a :<|> enter e b

38

52

39−instance (Enter b arg ret) => Enter (a -> b) arg (a -> ret) where

53+instance

54+ ( Entered m n (a -> typ) ~ (a -> ret)

55+ , Entered n m (a -> ret) ~ (a -> typ)

56+ , Enter typ m n ret

57+ )

58+ => Enter (a -> typ) m n (a -> ret)

59+ where

40 enter arg f a = enter arg (f a)

60 enter arg f a = enter arg (f a)

41

61

42-- ** Useful instances

62-- ** Useful instances

43

63

44−instance Enter (m a) (m :~> n) (n a) where

64+instance Enter (m a) m n (n a) where

45 enter (NT f) = f

65 enter (NT f) = f

46

66

47-- | Like `lift`.

67-- | Like `lift`.