This chapter describes standard predicates, which are always available to the Prolog interpreter, and do not need to be imported or loaded explicitly as do other Prolog predicates. By default, it is a compiler error to redefine standard predicates.
In the description below, certain standard predicates depend on HiLog semantics; the description of such predicates have the token HiLog at the right of the page. Similarly predicates that depend on SLG evaluation are marked as Tabling, and predicates whose semantics is defined by the ISO standard (or whose implementation is reasonably close to that definition) are marked as ISO. Occasionally, however, we include in this section predicates that are not standard. In such cases we denote their module in text font towards the middle of the page.