MonadState instance for QueueManager

1 files changed, 4 insertions, 1 deletions

diff --git a/server/src/Thermoprint/Server/Queue.hs b/server/src/Thermoprint/Server/Queue.hs
index 832b876..d5ab42b 100644
--- a/server/src/Thermoprint/Server/Queue.hs
+++ b/server/src/Thermoprint/Server/Queue.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE FlexibleInstances, FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances, FlexibleContexts, MultiParamTypeClasses #-}
 {-# LANGUAGE ViewPatterns #-}
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE DeriveGeneric, DeriveAnyClass #-}
@@ -125,6 +125,9 @@ toZipper = Set.foldr' insert def
 type QueueManager t = QueueManagerM t (Extended Micro)
 type QueueManagerM t = ComposeT (StateT Queue) t STM
 
+instance (Monad (StateT s (g m)), Monad (g m)) => MonadState s (ComposeT (StateT s) g m) where
+  state = ComposeT . state
+
 runQM :: ( HasQueue q
          , MFunctor t
          , MonadTrans t