:typing support about pddlstream HOT 2 CLOSED

Types are effectively just unary predicates, both in theory as well as in practice within FastDownward. Because of this, I've decided to not support them as a separate feature since they do not add expressiveness.

The set of preconditions does directly determine the number of action instances that are grounded for a finite set of objects. Look to add (static) preconditions involving several action parameters that are dependent on each other. For example, in a robotics application, a pose ?p is typically only well-defined for a single object ?o, which can be indicated by (Pose ?o ?p) and included in action/stream conditions (https://github.com/caelan/pddlstream/blob/main/examples/pybullet/pr2/stream.pddl#L16).

I've been able to plan in domains with actions that have a large number of parameters without a performance hit by following this general strategy (https://github.com/caelan/LTAMP/blob/7e0a28dca1156b1dc6d3b9459fed58607249c3ed/plan_tools/pddl/domain.pddl#L91).

from pddlstream.

Ah that makes sense. I should have checked what FastDownward actually uses. Much appreciated!

from pddlstream.