From 3ff97aca771fe1457054fa593019439bb86552ed Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gregor.kleen@ifi.lmu.de>
Date: Tue, 23 Mar 2021 15:52:28 +0100
Subject: [PATCH] refactor: hlint

---
 src/Utils/DB.hs | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/src/Utils/DB.hs b/src/Utils/DB.hs
index 05ec0516b..b0e48be1c 100644
--- a/src/Utils/DB.hs
+++ b/src/Utils/DB.hs
@@ -188,7 +188,7 @@ class WithRunDB backend m' m | m -> backend m' where
 instance WithRunDB backend m (ReaderT backend m) where
   useRunDB = id
 
-data DBRunner' backend m = DBRunner' { runDBRunner' :: forall b. ReaderT backend m b -> m b }
+newtype DBRunner' backend m = DBRunner' { runDBRunner' :: forall b. ReaderT backend m b -> m b }
 
 _DBRunner' :: Iso' (DBRunner site) (DBRunner' (YesodPersistBackend site) (HandlerFor site))
 _DBRunner' = iso fromDBRunner' toDBRunner
@@ -210,7 +210,7 @@ newtype CachedDBRunner backend m a = CachedDBRunner { runCachedDBRunnerUsing ::
   deriving (Functor, Applicative, Monad, MonadFix, MonadFail, Contravariant, MonadIO, Alternative, MonadPlus, MonadUnliftIO, MonadResource, MonadLogger, MonadThrow, MonadCatch, MonadMask) via (ReaderT (m (DBRunner' backend m)) m)
 
 instance MonadTrans (CachedDBRunner backend) where
-  lift act = CachedDBRunner (\_ -> act)
+  lift act = CachedDBRunner (const act)
 
 instance MonadHandler m => MonadHandler (CachedDBRunner backend m) where
   type HandlerSite (CachedDBRunner backend m) = HandlerSite m
@@ -238,10 +238,6 @@ runCachedDBRunnerSTM doAcquire act = do
             runner <- doAcquire
             void . atomically $ tryPutTMVar runnerTMVar runner
             return runner
-      getRunnerNoLock = do
-        cachedRunner <- atomically $ tryReadTMVar runnerTMVar
-        case cachedRunner of
-          Just cachedRunner' -> return cachedRunner'
-          Nothing -> getRunner
+      getRunnerNoLock = maybe getRunner return =<< atomically (tryReadTMVar runnerTMVar)
   
   runCachedDBRunnerUsing act getRunnerNoLock