diff --git a/loup.cabal b/loup.cabal
--- a/loup.cabal
+++ b/loup.cabal
@@ -1,5 +1,5 @@
 name: loup
-version: 0.0.14
+version: 0.0.15
 cabal-version: >=1.22
 build-type: Simple
 license: MIT
@@ -29,7 +29,7 @@
         conduit >=1.2.10,
         lifted-async >=0.9.1.1,
         lifted-base >=0.2.3.11,
-        preamble >=0.0.48,
+        preamble >=0.0.49,
         time >=1.5.0.1,
         turtle >=1.3.6,
         unordered-containers >=0.2.8.0,
@@ -84,7 +84,7 @@
     main-is: Shakefile.hs
     build-depends:
         base >=4.8 && <5,
-        shakers >=0.0.28
+        shakers >=0.0.31
     default-language: Haskell2010
     ghc-options: -threaded -rtsopts -with-rtsopts=-N -Wall
 
diff --git a/src/Network/AWS/Loup/Act.hs b/src/Network/AWS/Loup/Act.hs
--- a/src/Network/AWS/Loup/Act.hs
+++ b/src/Network/AWS/Loup/Act.hs
@@ -26,7 +26,7 @@
 pollActivity domain list =
   runResourceT $ runAmazonCtx $ do
     pfatrs <- send $ pollForActivityTask domain list
-    return (pfatrs ^. pfatrsTaskToken, pfatrs ^. pfatrsInput)
+    pure (pfatrs ^. pfatrsTaskToken, pfatrs ^. pfatrsInput)
 
 -- | Cancel activity.
 --
@@ -48,7 +48,7 @@
 heartbeat token =
   runResourceT $ runAmazonCtx $ do
     rathrs <- send $ recordActivityTaskHeartbeat token
-    return $ rathrs ^. rathrsCancelRequested
+    pure (rathrs ^. rathrsCancelRequested)
 
 -- | Run a managed action inside a temp directory.
 --
diff --git a/src/Network/AWS/Loup/Converge.hs b/src/Network/AWS/Loup/Converge.hs
--- a/src/Network/AWS/Loup/Converge.hs
+++ b/src/Network/AWS/Loup/Converge.hs
@@ -26,9 +26,9 @@
   runResourceT $ runAmazonCtx $ do
     let etf = executionTimeFilter $ posixSecondsToUTCTime $ fromIntegral (0 :: Int)
         wtf = workflowTypeFilter (activity ^. atName)
-    weis <- pages $ set loweTypeFilter (return wtf) $ listOpenWorkflowExecutions domain etf
+    weis <- pages $ set loweTypeFilter (pure wtf) $ listOpenWorkflowExecutions domain etf
     let predicate wei = maybe True not $ wei ^. weiCancelRequested
-    return $ view weWorkflowId . view weiExecution <$> filter predicate (join $ view weiExecutionInfos <$> weis)
+    pure $ view weWorkflowId . view weiExecution <$> filter predicate (join $ view weiExecutionInfos <$> weis)
 
 -- | Start a workflow.
 --
@@ -37,7 +37,7 @@
   runResourceT $ runAmazonCtx $ do
     let wt = workflowType (activity ^. atName) (activity ^. atVersion)
     void $ send $ startWorkflowExecution domain wid wt
-      & sTaskList .~ return list
+      & sTaskList .~ pure list
       & sInput .~ input
 
 -- | Cancel a workflow.
@@ -57,7 +57,7 @@
     let fold kvs as action = do
           let g k v bs = do
                 let k' = k -.- textShow (hash v)
-                if k' `member` bs then return $ k' `delete` bs else action k' v >> return bs
+                if k' `member` bs then pure $ k' `delete` bs else action k' v >> pure bs
           ifoldrM g as kvs
     wids' <- fold (pool ^. pWorkers) wids $ \wid input -> do
       traceInfo "start" [ "wid" .= wid, "input" .= input ]
diff --git a/src/Network/AWS/Loup/Ctx.hs b/src/Network/AWS/Loup/Ctx.hs
--- a/src/Network/AWS/Loup/Ctx.hs
+++ b/src/Network/AWS/Loup/Ctx.hs
@@ -30,7 +30,7 @@
 botErrorCatch ex = do
   case ex of
     TransportError _ ->
-      return ()
+      pure ()
     _ ->
       traceError "exception" [ "error" .= displayException ex ]
   throwIO ex
diff --git a/src/Network/AWS/Loup/Decide.hs b/src/Network/AWS/Loup/Decide.hs
--- a/src/Network/AWS/Loup/Decide.hs
+++ b/src/Network/AWS/Loup/Decide.hs
@@ -25,7 +25,7 @@
 pollDecision domain list =
   runResourceT $ runAmazonCtx $ do
     pfdtrs <- pages $ pollForDecisionTask domain list
-    return (join $ headMay $ view pfdtrsTaskToken <$> pfdtrs, reverse $ join $ view pfdtrsEvents <$> pfdtrs)
+    pure (join $ headMay $ view pfdtrsTaskToken <$> pfdtrs, reverse $ join $ view pfdtrsEvents <$> pfdtrs)
 
 -- | Successful decision completion.
 --
@@ -40,10 +40,10 @@
 scheduleActivity :: UUID -> ActivityType -> TaskList -> Maybe Text -> Decision
 scheduleActivity uid activity list input = do
   let satda = scheduleActivityTaskDecisionAttributes activity (toText uid)
-        & satdaTaskList .~ return list
+        & satdaTaskList .~ pure list
         & satdaInput    .~ input
   decision ScheduleActivityTask
-    & dScheduleActivityTaskDecisionAttributes .~ return satda
+    & dScheduleActivityTaskDecisionAttributes .~ pure satda
 
 -- | Complete activity decision.
 --
@@ -51,7 +51,7 @@
 completeActivity = do
   let cweda = completeWorkflowExecutionDecisionAttributes
   decision CompleteWorkflowExecution
-    & dCompleteWorkflowExecutionDecisionAttributes .~ return cweda
+    & dCompleteWorkflowExecutionDecisionAttributes .~ pure cweda
 
 -- | Cancel activity decision.
 --
@@ -59,7 +59,7 @@
 cancelActivity = do
   let cweda = cancelWorkflowExecutionDecisionAttributes
   decision CancelWorkflowExecution
-    & dCancelWorkflowExecutionDecisionAttributes .~ return cweda
+    & dCancelWorkflowExecutionDecisionAttributes .~ pure cweda
 
 -- | Request to cancel activity decision.
 --
@@ -67,14 +67,14 @@
 requestCancel uid = do
   let rcatda = requestCancelActivityTaskDecisionAttributes (toText uid)
   decision RequestCancelActivityTask
-    & dRequestCancelActivityTaskDecisionAttributes .~ return rcatda
+    & dRequestCancelActivityTaskDecisionAttributes .~ pure rcatda
 
 -- | Find a matching event type.
 --
 findEvent :: MonadDecisionCtx c m => EventType -> m (Maybe HistoryEvent)
 findEvent eventType = do
-  let f []     = return Nothing
-      f (e:es) = bool (f es) (return $ Just e) $ e ^. heEventType == eventType
+  let f []     = pure Nothing
+      f (e:es) = bool (f es) (pure $ Just e) $ e ^. heEventType == eventType
   events <- view dcEvents
   f events
 
@@ -86,7 +86,7 @@
   uid  <- liftIO nextRandom
   task <- view pActivityTask <$> view dcPlan
   let input = join $ view weseaInput <$> event ^. heWorkflowExecutionStartedEventAttributes
-  return [ scheduleActivity uid (task ^. tActivityType) (task ^. tTaskList) input ]
+  pure [ scheduleActivity uid (task ^. tActivityType) (task ^. tTaskList) input ]
 
 -- | Cancel workflow step.
 --
@@ -95,14 +95,14 @@
   traceInfo "cancel" mempty
   event <- findEvent ActivityTaskScheduled
   let uid = join $ fromText . view atseaActivityId <$> join (view heActivityTaskScheduledEventAttributes <$> event)
-  return [ maybe cancelActivity requestCancel uid ]
+  pure [ maybe cancelActivity requestCancel uid ]
 
 -- | Completed workflow step.
 --
 completed :: MonadDecisionCtx c m => m [Decision]
 completed = do
   traceInfo "completed" mempty
-  return [ completeActivity ]
+  pure [ completeActivity ]
 
 -- | Restart workflow step.
 --
@@ -113,14 +113,14 @@
   task  <- view pActivityTask <$> view dcPlan
   event <- findEvent WorkflowExecutionStarted
   let input = join $ view weseaInput <$> join (view heWorkflowExecutionStartedEventAttributes <$> event)
-  return [ scheduleActivity uid (task ^. tActivityType) (task ^. tTaskList) input ]
+  pure [ scheduleActivity uid (task ^. tActivityType) (task ^. tTaskList) input ]
 
 -- | Cancel failed workflow step.
 --
 canceled :: MonadDecisionCtx c m => m [Decision]
 canceled = do
   traceInfo "canceled" mempty
-  return [ cancelActivity ]
+  pure [ cancelActivity ]
 
 -- | When we run out of events.
 --
@@ -128,7 +128,7 @@
 nothing = do
   events <- view dcEvents
   traceError "none" [ "events" .= (textShow . view heEventType <$> events) ]
-  return mempty
+  pure mempty
 
 -- | Schedule decision based on history events.
 --