Fix deriving instance of MonadUnliftIO

I'm getting trouble from MonadUnliftIO when building the project
using stack

 src/Language/LSP/Server/Core.hs:75:63: error:
     • Couldn't match representation of type ‘m (UnliftIO
                                                   (LspT config m))’
                                with that of ‘m (UnliftIO (ReaderT (LanguageContextEnv config) m))’
         arising from the coercion of the method ‘askUnliftIO’
           from type ‘ReaderT
                        (LanguageContextEnv config)
                        m
                        (UnliftIO (ReaderT (LanguageContextEnv config) m))’
             to type ‘LspT config m (UnliftIO (LspT config m))’
       NB: We cannot know what roles the parameters to ‘m’ have;
         we must assume that the role is nominal
     • When deriving the instance for (MonadUnliftIO (LspT config m))
    |
 75 |   deriving (Functor, Applicative, Monad, MonadIO, MonadTrans, MonadUnliftIO, MonadFix)
    |                                                               ^^^^^^^^^^^^^

Author: banacorn

src/Language/LSP/Server/Core.hs

@@ -72,7 +72,15 @@ import           Control.Monad.Trans.Identity
 -- ---------------------------------------------------------------------
 
 newtype LspT config m a = LspT { unLspT :: ReaderT (LanguageContextEnv config) m a }
-  deriving (Functor, Applicative, Monad, MonadIO, MonadTrans, MonadUnliftIO, MonadFix)
+  deriving (Functor, Applicative, Monad, MonadIO, MonadTrans, MonadFix)
+
+-- Manually deriving LspT as an instance of MonadUnliftIO
+instance MonadUnliftIO m => MonadUnliftIO (LspT config m) where 
+  withRunInIO inner = 
+    LspT $ 
+    ReaderT $ \config -> 
+      withRunInIO $ \run -> 
+        inner (run . flip runReaderT config . unLspT)
 
 runLspT :: LanguageContextEnv config -> LspT config m a -> m a
 runLspT env = flip runReaderT env . unLspT