[m-dev.] set__power_intersect

[Andrew Bromage]

G'day.

Fergus wrote:

> Currently
> 
> 	?- set__init(S0), set__power_intersect(S0, S).
> 
> will return `S = []'.  That definition doesn't make much sense to me.
> I think perhaps it would be better to call error/1 in this case.

You're right, it should.  Though of course it could return a meaningful
answer if the type has a finite number of elements...

Cheers,
Andrew Bromage