consensus: add Strict.newTVar

Author: nfrisby

strict-stm/src/Control/Monad/Class/MonadSTM/Strict.hs

@@ -23,6 +23,7 @@ module Control.Monad.Class.MonadSTM.Strict
   , fromLazyTVar
   , newTVar
   , newTVarIO
+  , newTVarWithInvariant
   , newTVarWithInvariantIO
   , readTVar
   , readTVarIO
@@ -149,6 +150,15 @@ newTVarM :: MonadSTM m => a -> m (StrictTVar m a)
 newTVarM = newTVarIO
 {-# DEPRECATED newTVarM "Use newTVarIO" #-}
 
+newTVarWithInvariant :: (MonadSTM m, HasCallStack)
+                     => (a -> Maybe String) -- ^ Invariant (expect 'Nothing')
+                     -> a
+                     -> STM m (StrictTVar m a)
+newTVarWithInvariant  invariant !a =
+        checkInvariant (invariant a) $
+        (\tvar -> mkStrictTVar invariant tvar)
+    <$> Lazy.newTVar a
+
 newTVarWithInvariantIO :: (MonadSTM m, HasCallStack)
                        => (a -> Maybe String) -- ^ Invariant (expect 'Nothing')
                        -> a