si-timers: mtl instances for MonadMonotonicTime

Author: coot

si-timers/src/Control/Monad/Class/MonadTime/SI.hs

@@ -17,6 +17,12 @@ module Control.Monad.Class.MonadTime.SI
   , NominalDiffTime
   ) where
 
+import           Control.Monad.Cont
+import           Control.Monad.RWS
+import           Control.Monad.Reader
+import           Control.Monad.State
+import           Control.Monad.Writer
+
 import           Control.Monad.Class.MonadTime ( MonadMonotonicTimeNSec,
                      MonadTime (..), NominalDiffTime, UTCTime, diffUTCTime,
                      addUTCTime)
@@ -56,3 +62,22 @@ class MonadMonotonicTimeNSec m => MonadMonotonicTime m where
         conv = Time . Time.picosecondsToDiffTime . (* 1_000) . toInteger
 
 instance MonadMonotonicTime IO where
+
+--
+-- MTL instances
+--
+
+instance MonadMonotonicTime m => MonadMonotonicTime (ReaderT r m) where
+  getMonotonicTime = lift getMonotonicTime
+
+instance MonadMonotonicTime m => MonadMonotonicTime (StateT s m) where
+  getMonotonicTime = lift getMonotonicTime
+
+instance (Monoid w, MonadMonotonicTime m) => MonadMonotonicTime (WriterT w m) where
+  getMonotonicTime = lift getMonotonicTime
+
+instance (Monoid w, MonadMonotonicTime m) => MonadMonotonicTime (RWST r w s m) where
+  getMonotonicTime = lift getMonotonicTime
+
+instance MonadMonotonicTime m => MonadMonotonicTime (ContT r m) where
+  getMonotonicTime = lift getMonotonicTime