[eclipse-clp-users] Finite domain with partial order

Hello,
I'm trying to implement a (prototype of a) type system in Eclipse using constraint handling rules. The problem is that the domain of types is partially ordered. For example, if we take integers, reals and strings, I would like integer < real but not string < integer or string > integer. I'm currently using the FD solver for this, representing each type with an integer, but that is not really convenient, since I have to keep checking that the comparisons are actually valid.
Is there an "official" way of using partial orders in eclipse? I didn't see anything in the manual. I suppose I could try the FD_Sets solver, because the subset relation is a partial order, or I could try the SD solver and somehow define my own < relation, but either sounds straightforward.

Regards,
Arjan van der Meer