While developing MobilityDB we needed to extend the range type operators so they cope with elements. In the same way that currently the range types support both - @> contains range/element - <@ element/range is contained by we extended the left (<<), overleft (&<), right (>>), and overright (&>) operators so they can cope with both elements and ranges at the left- or right-hand side. These can be seen in github https://github.com/ULB-CoDE-WIT/MobilityDB/blob/master/src/rangetypes_ext.c
If you think that these extensions could be useful for the community at large, I can prepare a PR. Please let me know.
