(Only alpha tested)
View rules are single source path problem rules which consist of a linear chain
of predicates and one single assigned predicate.
In order to faciliate the writing of rule tests, these assigned predicates can
be used as abbreviation for the complete view rule.
Thus, if the user uses in a rule test an assigned predicate of a view rule, the
rule test part of the rule is expanded in-line into the using rule.
This works without problems because the view rule is only allowed to have chain
form.
In order to define view rules the user must specify the assigned predicate in a
DECLARE specification as follows:
Rules which define this assigned predicate are assumed to be view rules and are automatically inline-expanded in other rules. Note that only one view rule per view assigned predicate may exist.
Global sets which assemble the assigned predicate elements can be choosen from any set or list functor.
