SWI-Prolog -- lazy

Create a lazy list from a callback. Next is called repeatedly to extend the list. It is called as call(Next, List, Tail), where the difference list List\Tail produces the next slice of the list. If the end of the input is reached, List must be a proper list and Tail must be [].

bug: - The content returned by the iterator is duplicated in nb_setarg/3. This is needed by avoid the risk of trailed assignments in the structure. Avoiding this duplication would significantly reduce the overhead.