include "primitives.alh"

SimpleAttribute Natural {
	constraint = $
		String function constraint(model : Element, name : String):
			if (bool_not(is_physical_int(model["model"][name]))):
				return "Natural has no integer value"!
			elif (integer_lt(model["model"][name], 0)):
				return "Natural does not have a positive or zero value"!
			else:
				return "OK"!
		$
}
Class Place{
	tokens : Natural
}
Class Transition{}
Association P2T (Place, Transition) {
	weight : Natural
}
Association T2P (Transition, Place) {
	weight : Natural
}