Add MonadBaseControl IO ClientM instance

Author: phadej

servant-client/servant-client.cabal

@@ -47,12 +47,14 @@ library
     , http-client-tls       >= 0.2.2    && < 0.4
     , http-media            >= 0.6.2    && < 0.7
     , http-types            >= 0.8.6    && < 0.10
+    , monad-control         >= 1.0.0.4  && < 1.1
     , network-uri           >= 2.6      && < 2.7
     , safe                  >= 0.3.9    && < 0.4
     , servant               == 0.9.*
     , string-conversions    >= 0.3      && < 0.5
     , text                  >= 1.2      && < 1.3
     , transformers          >= 0.3      && < 0.6
+    , transformers-base     >= 0.4.4    && < 0.5
     , transformers-compat   >= 0.4      && < 0.6
     , mtl
   hs-source-dirs: src

servant-client/src/Servant/Common/Req.hs

@@ -1,9 +1,11 @@
-{-# LANGUAGE DeriveDataTypeable  #-}
-{-# LANGUAGE DeriveGeneric       #-}
-{-# LANGUAGE CPP                 #-}
-{-# LANGUAGE OverloadedStrings   #-}
-{-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE GeneralizedNewtypeDeriving   #-}
+{-# LANGUAGE CPP                        #-}
+{-# LANGUAGE DeriveDataTypeable         #-}
+{-# LANGUAGE DeriveGeneric              #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE MultiParamTypeClasses      #-}
+{-# LANGUAGE TypeFamilies               #-}
+{-# LANGUAGE OverloadedStrings          #-}
+{-# LANGUAGE ScopedTypeVariables        #-}
 
 module Servant.Common.Req where
 
@@ -24,8 +26,10 @@ import Control.Monad.Trans.Except
 
 
 import GHC.Generics
+import Control.Monad.Base (MonadBase (..))
 import Control.Monad.IO.Class ()
 import Control.Monad.Reader
+import Control.Monad.Trans.Control (MonadBaseControl (..))
 import Data.ByteString.Lazy hiding (pack, filter, map, null, elem, any)
 import Data.String
 import Data.String.Conversions
@@ -180,6 +184,18 @@ newtype ClientM a = ClientM { runClientM' :: ReaderT ClientEnv (ExceptT ServantE
                              , MonadThrow, MonadCatch
                              )
 
+instance MonadBase IO ClientM where
+  liftBase = ClientM . liftBase
+
+instance MonadBaseControl IO ClientM where
+  type StM ClientM a = Either ServantError a
+
+  -- liftBaseWith :: (RunInBase ClientM IO -> IO a) -> ClientM a
+  liftBaseWith f = ClientM (liftBaseWith (\g -> f (g . runClientM')))
+
+  -- restoreM :: StM ClientM a -> ClientM a
+  restoreM st = ClientM (restoreM st)
+
 runClientM :: ClientM a -> ClientEnv -> IO (Either ServantError a)
 runClientM cm env = runExceptT $ (flip runReaderT env) $ runClientM' cm