This would improve maintainability of code by eliminating need for missing checks for x < 0, etc.

java.lang.Long is mentioned here because things are moving to where what we carry around are AnyRef, not Any; hence, the numbers must be objects, not AnyVal types. (ULong is AnyVal today. We need an AnyRef variant of it).

In other words, as Long is to java.lang.Long, so ULong is to ??