object
optional
¶
Constructors for optional term references. A reference is either empty or holds a term. References should be regarded as opaque terms and always used with the optional/1
object by passing the reference as a parameter.
Author: Paulo Moura
Version: 1.4
Date: 2019/1/23
Compilation flags:
static, context_switching_calls
Provides:
Remarks:
Type-checking support: This object also defines a type
optional
for use with thetype
library object.
Public predicates¶
empty/1
¶
Constructs an empty reference.
Compilation flags:
static
Template:
empty(Reference)
Mode and number of proofs:
empty(--nonvar)
- one
of/2
¶
Constructs a reference holding a term.
Compilation flags:
static
Template:
of(Term,Reference)
Mode and number of proofs:
of(@term,--nonvar)
- one
from_goal/3
¶
Constructs a reference by calling Goal
that binds and holds Term
on success. Returns an empty reference if the goal fails or throws an error.
Compilation flags:
static
Template:
from_goal(Goal,Term,Reference)
Meta-predicate template:
from_goal(0,*,*)
Mode and number of proofs:
from_goal(+callable,--term,--nonvar)
- one
Protected predicates¶
(see entity ancestors)
Private predicates¶
(see entity ancestors)