As discussed in #196:
Instead of introducing AssertionResult, EvalInt should be answered and it should be queried in Base in eval_rv_pre. To avoid infinite recursion, eval_rv could get a new optional parameter that disallows ask and this way a cycle would not happen. When base gets asked about EvalInt it will only answer what it knows if eval_rv has a true there. In other places where we have calls to eval_rv the argument would have a default value false. I'll implement this solution and make a commit. If you know a better one, please propose it.