Module cont

This module allows accessing the continuation queue and the verify flag. The predicate sys_assume_cont/1 will push a delayed goal. This predicate will also place an undo handler on the trail that will pop the delayed goal upon backtracking.

When the verify flag allows it the whole continuation queue is executed either on the next exit port of a built-in or the next unification port of a defined predicate. The verify flag is automati-cally disabled during execution of attribute variable hook.

The following continuation queue predicates are provided:

sys_assume_cont(G):
The predicate temporarily pushes the goal G on the continuation queue.
sys_ripple(A):
The predicate succeeds whenever A succeeds. The goal A is invoked with the verify flag temporarily set to off.

The following Prolog flags for continuation queue are provided:

sys_verify:
Legal values are on and off. The flag indicates whether the interpreter currently executes continuations. Default value is on. The value can be changed.

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