This section describes the annotations of predicates and how they are indicated in the reference pages for predicates of each given annotation. The annotations appear to the right of the title of the reference page.
The behavior of the predicate can be customized/redefined by defining one or more hooks. The mode and type annotations of a hookable predicate might not be absolute, since hooks added by the user can change the behavior.
The predicate is user defined, and is called by a hookable
builtin. Typically, it is undefined initially, belongs to the
module, and if defined by the user, it is best defined as multifile,
so that new clauses can be added by different software modules. For a
hook, the mode and type annotations should be seen as guidelines to
the user who wants to add his own hook; they describe how the
predicate is used by the system.
You cannot call these directly but they can appear in files as ‘:- declaration’ and give information to the compiler. The goal template is preceded by ‘:-’ in the Synopsis.
A predicate that is defined in the development system only, i.e. not in runtime systems.
A predicate that is part of the ISO Prolog Standard.
A predicate that is not recommended in new code and that could be withdrawn in a future release.
Meta-predicates and operators are recognizable by the implicit conventions described below.
If no module prefix is supplied, then it will implicitly be set to the calling module. If the module prefix is a variable, then an instantiation error will be raised. If it is not an atom, then a type error will be raised. So in any meta-predicate reference page the following exceptions are implicit:
A module prefix is written as a variable.
A module prefix is not an atom.
:- initialization+Goal (A) +Term1
It is thus always possible to see if a name is an operator or not. The predicate can, of course, be written using the canonical representation, even when the name is an operator. Thus (A) and (B) can be written as (C) and (D), respectively:
@>(+Term1, +Term2) (D)