[boost] [Interval] Conversion from integer types?

Can someone explain what the issue is in converting an integer type to a boost::interval, and in performing mixed integer/floating point arithmetic and comparisons? Is it simply that the integer types may have more bits in their representation than floating point ones, and we may therefore loose precision? If so, can we not convert integers to intervals implicitly, complete with calculation of the error? That would auto-magically make mixed integer/floating point arithmetic work as well. And yes, I'm prepared to invest some time to make this work and do the right thing, if time is the only stumbling block :-) Thanks, John.