Multi-domains operations

[ptal]

For example, and for genericity purposes, it could be convenient to implement Contains<Interval<Bound>> for Bound, however does it really makes sense?

Another problem is the high number of combination between domains... To avoid this, should we cast less precise domains to more precise ones? But this is problematic for true generic programming and to propose efficient algorithms...

[ptal]

This is a problematic partially resolved by gcollections. However it remains to implement comparison between two non-ground types, such as between Interval and IntervalSet.