I think it's great to see this. I was really impressed by the insight/design of allowing the user to specify the invalidation functions, rather than trying to

I think it's great to see this. I was really impressed by the insight/design of allowing the user to specify the invalidation functions, rather than trying to solve the (very difficult) problem of automatically determining the exact set of invalidation criteria. It may be that the user can determine a better invalidation function anyway, because they have domain-specific knowledge (e.g. how often a table changes). (I'm a meteorite, but commenting in my personal capacity)