approximate log stack in handleLogDiscard

lib/Quox/Log.idr

@@ -289,3 +289,16 @@ handleLogDiscardIO : HasIO m => MonadRec m => IORef Nat ->
                      LogL tag a -> m a
 handleLogDiscardIO ref act =
   runEff (handleLogDiscard_ act) [handleStateIORef ref]
+
+
+||| approximate the push/pop effects in a discarded log by trimming a stack or
+||| repeating its most recent element
+export %inline
+fixupDiscardedLog : Nat -> LevelStack -> LevelStack
+fixupDiscardedLog want lvls =
+  let len = length lvls in
+  case compare len want of
+    EQ => lvls
+    GT => drop (len `minus` want) lvls
+    LT => let new = fromMaybe defaultLogLevels $ head' lvls in
+          replicate (want `minus` len) new ++ lvls