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.. index:: single: datalog_protocol .. _datalog_protocol/0:
.. rst-class:: right
protocol
datalog_protocol
Datalog and incremental rule engine protocol (stratified negation subset).
| Availability:
| logtalk_load(datalog(loader))
| Author: Paulo Moura | Version: 0:1:0 | Date: 2026-02-13
| Compilation flags:
| static
| Dependencies: | (none)
| Remarks:
- Rules: Rules are represented as
rule(Id, Head, Body)whereBodyis a list of literals usingTermfor positive,neg(Term)for negative, andagg(Op, Template, Goals, Result)for aggregates whereOpis one ofcount,sum,min, ormax. - Facts: EDB facts are represented by callable and ground terms.
- Limitations: Current version requires aggregate dependencies to be in lower strata.
| Inherited public predicates: | (none)
.. contents:: :local: :backlinks: top
Public predicates
.. index:: clear/0 .. _datalog_protocol/0::clear/0:
clear/0 ^^^^^^^^^^^
Clears all loaded rules, base facts, derived facts, and explanation supports.
| Compilation flags:
| static
| Mode and number of proofs:
| clear - one
.. index:: load_program/1 .. _datalog_protocol/0::load_program/1:
load_program/1 ^^^^^^^^^^^^^^^^^^
Loads a full program represented as a list of rule(Id,Head,Body) and fact(Fact) terms, replacing current engine state.
| Compilation flags:
| static
| Template:
| load_program(Program)
| Mode and number of proofs:
| load_program(+list) - one
.. index:: add_rule/3 .. _datalog_protocol/0::add_rule/3:
add_rule/3 ^^^^^^^^^^^^^^
Adds or replaces a rule. Rule safety is checked.
| Compilation flags:
| static
| Template:
| add_rule(Id,Head,Body)
| Mode and number of proofs:
| add_rule(+nonvar,+callable,+list(callable)) - one
.. index:: remove_rule/1 .. _datalog_protocol/0::remove_rule/1:
remove_rule/1 ^^^^^^^^^^^^^^^^^
Removes all rules matching a rule identifier.
| Compilation flags:
| static
| Template:
| remove_rule(Id)
| Mode and number of proofs:
| remove_rule(+nonvar) - one
.. index:: begin/0 .. _datalog_protocol/0::begin/0:
begin/0 ^^^^^^^^^^^
Starts a transaction by saving the current engine state snapshot.
| Compilation flags:
| static
| Mode and number of proofs:
| begin - one
.. index:: commit/0 .. _datalog_protocol/0::commit/0:
commit/0 ^^^^^^^^^^^^
Commits a transaction by discarding the saved state snapshot.
| Compilation flags:
| static
| Mode and number of proofs:
| commit - one
.. index:: rollback/0 .. _datalog_protocol/0::rollback/0:
rollback/0 ^^^^^^^^^^^^^^
Rolls back a transaction by restoring the saved state snapshot.
| Compilation flags:
| static
| Mode and number of proofs:
| rollback - one
.. index:: assert_fact/1 .. _datalog_protocol/0::assert_fact/1:
assert_fact/1 ^^^^^^^^^^^^^^^^^
Asserts a ground EDB fact if not already present.
| Compilation flags:
| static
| Template:
| assert_fact(Fact)
| Mode and number of proofs:
| assert_fact(+callable) - one
.. index:: retract_fact/1 .. _datalog_protocol/0::retract_fact/1:
retract_fact/1 ^^^^^^^^^^^^^^^^^^
Retracts an EDB fact if present.
| Compilation flags:
| static
| Template:
| retract_fact(Fact)
| Mode and number of proofs:
| retract_fact(+callable) - one
.. index:: materialize/0 .. _datalog_protocol/0::materialize/0:
materialize/0 ^^^^^^^^^^^^^^^^^
Computes rule closure from current EDB facts and loaded rules using a fixpoint algorithm.
| Compilation flags:
| static
| Mode and number of proofs:
| materialize - one
.. index:: update/3 .. _datalog_protocol/0::update/3:
update/3 ^^^^^^^^^^^^
Applies incremental EDB updates and propagates derivation additions/removals; returns the resulting truth delta.
| Compilation flags:
| static
| Template:
| update(Inserts,Deletes,Delta)
| Mode and number of proofs:
| update(+list(callable),+list(callable),-compound) - one
.. index:: query/1 .. _datalog_protocol/0::query/1:
query/1 ^^^^^^^^^^^
Enumerates currently true facts (EDB + IDB).
| Compilation flags:
| static
| Template:
| query(Goal)
| Mode and number of proofs:
| query(?callable) - zero_or_more
.. index:: query/2 .. _datalog_protocol/0::query/2:
query/2 ^^^^^^^^^^^
Same as query/1 while returning the unified goal as the second argument.
| Compilation flags:
| static
| Template:
| query(Goal,Bindings)
| Mode and number of proofs:
| query(?callable,?callable) - zero_or_more
.. index:: explain/2 .. _datalog_protocol/0::explain/2:
explain/2 ^^^^^^^^^^^^^
Returns one explanation for a currently true fact.
| Compilation flags:
| static
| Template:
| explain(Fact,Explanation)
| Mode and number of proofs:
| explain(+callable,-nonvar) - zero_or_more
.. index:: (rules)/1 .. _datalog_protocol/0::(rules)/1:
(rules)/1
^^^^^^^^^^^^^
Returns the loaded rules.
| Compilation flags:
| static
| Template:
| rules Rules
| Mode and number of proofs:
| rules-list - one
.. index:: facts/1 .. _datalog_protocol/0::facts/1:
facts/1 ^^^^^^^^^^^
Returns all currently true facts as a sorted list.
| Compilation flags:
| static
| Template:
| facts(Facts)
| Mode and number of proofs:
| facts(-list(callable)) - one
.. index:: predicate_stratum/3 .. _datalog_protocol/0::predicate_stratum/3:
predicate_stratum/3 ^^^^^^^^^^^^^^^^^^^^^^^
Enumerates predicate strata as functor, arity, and stratum number.
| Compilation flags:
| static
| Template:
| predicate_stratum(Functor,Arity,Stratum)
| Mode and number of proofs:
| predicate_stratum(?atom,?integer,?integer) - zero_or_more
.. index:: strata/1 .. _datalog_protocol/0::strata/1:
strata/1 ^^^^^^^^^^^^
Returns all strata grouped by stratum number and contained predicates.
| Compilation flags:
| static
| Template:
| strata(Strata)
| Mode and number of proofs:
| strata(-list) - one
Protected predicates
(none)
Private predicates
(none)
Operators
(none)