The PREDICATE() macros have a
number of variations that deal with special cases.
- PREDICATE(name,
arity)
- Create a predicate with an automatically generated internal name, and
register it with Prolog. The various term arguments are accessible as
A1, A2,
etc.
- PREDICATE0(name)
- This is the same as PREDICATE(name, 0). It avoids a compiler warning
that
PL_av is not used.
- NAMED_PREDICATE(plname,
cname, arity)
- This version can be used to create predicates whose name is not a valid
C++ identifier. Here is a ---hypothetical--- example, which unifies the
second argument with a stringified version of the first. The cname
is used to create a name for the functions. The concrete name does not
matter, but must be unique. Typically it is a descriptive name using the
limitations imposed by C++ indentifiers.
NAMED_PREDICATE("#", hash, 2)
{ return A2.unify_string(A1.as_string());
}
- PREDICATE_NONDET(name,
arity)
- Define a non-deterministic Prolog predicate in C++. See also
section 1.14.2.
- NAMED_PREDICATE_NONDET(plname,
cname, arity)
- Define a non-deterministic Prolog predicate in C++, whose name is not a
valid C++ identifier. See also section
1.14.2.
