From 95e66fa398b67080a2ee2cef00bd53dfc1d5ae04 Mon Sep 17 00:00:00 2001
From: Moritz Kiefer <moritz.kiefer@purelyfunctional.org>
Date: Sat, 3 Nov 2018 21:41:23 +0100
Subject: [PATCH] Add MonadMask instance for Handler

---
 servant-server/src/Servant/Server/Internal/Handler.hs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/servant-server/src/Servant/Server/Internal/Handler.hs b/servant-server/src/Servant/Server/Internal/Handler.hs
index c7e5f07d..82868629 100644
--- a/servant-server/src/Servant/Server/Internal/Handler.hs
+++ b/servant-server/src/Servant/Server/Internal/Handler.hs
@@ -11,7 +11,7 @@ import           Prelude.Compat
 import           Control.Monad.Base
                  (MonadBase (..))
 import           Control.Monad.Catch
-                 (MonadCatch, MonadThrow)
+                 (MonadCatch, MonadMask, MonadThrow)
 import           Control.Monad.Error.Class
                  (MonadError)
 import           Control.Monad.IO.Class
@@ -29,7 +29,7 @@ newtype Handler a = Handler { runHandler' :: ExceptT ServantErr IO a }
   deriving
     ( Functor, Applicative, Monad, MonadIO, Generic
     , MonadError ServantErr
-    , MonadThrow, MonadCatch
+    , MonadThrow, MonadCatch, MonadMask
     )
 
 instance MonadBase IO Handler where