merge :: GCompare k => DMap (WrapArg Event k) -> Event (DMap k)
merge m = EventMerge $ Merge
  { mergeParents = m
  , mergeSubscribed = unsafeNewIORef m Nothing
  }
merge :: GCompare k => DMap (WrapArg Event k) -> Event (DMap k)
merge m = EventMerge $ Merge
  { mergeParents = m
  , mergeSubscribed = unsafeNewIORef m Nothing
  }
merge m = EventMerge $ Merge
  { mergeParents = m
  , mergeSubscribed = unsafeNewIORef m Nothing
  }