Roaring bitmaps are integer sets with optimized set-wise operations, like intersecting two sets to find out which integers are contained by both. Judy is an ass

Roaring bitmaps are integer sets with optimized set-wise operations, like intersecting two sets to find out which integers are contained by both. Judy is an associate array (so it's interface is similar to a hash table). There's a specialized case for word->bit, but no set-wise operations and no way to match the performance of roaring for those. This doesn't quite answer your question, but if Roaring fits your case you should use it instead of Judy1 even if have Judy1 available.