facts-db/cl-facts/README.md
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Hash : 75dd88dc
Author :
Thomas de Grivel
Date : 2023-07-11T13:59:11
fixed bug in cl-compare
facts-db/cl-facts
1.1 The world is the totality of facts, not of things.
– Ludwig Wittgenstein, Tractatus Logico Philosophicus
cl-facts is a small in-memory graph database for Common Lisp. It features :
- a triple store based on unlabelled skip lists
- a very simple query language (facts:with)
- transactions using rollback functions
- logging and replay of transactions to/from disk
- dumping and loading the database to/from disk
Requirements
You will need :
Usage
FACTS:ADD &rest SPECS
Adds facts (triples) to the database. Triples can be grouped by subject.
(facts:add ("Blade Runner" :is-a :movie
:director "Ridley Scott"
:actor "Harison Ford"
:actor "Rutger Hauer")
("Snow White" :is-a :movie
:director "William Cottrell"
:director "David Hand"))
or either
(facts:add (?movie :is-a :movie
:title "Blade Runner"
:director "Ridley Scott"
:actor "Harrison Ford"
:actor "Rutger Hauer"))
(facts:add (?movie :is-a :movie
:title "Snow White and the Seven Dwarfs"
:director "William Cottrell"
:director "David Hand"))
(with ((?s ?p ?o))
(format t "~&~S ~S ~S~&" ?s ?p ?o))
FACTS.ANON::MOVIE-0000 :ACTOR "Harison Ford"
FACTS.ANON::MOVIE-0000 :ACTOR "Rutger Hauer"
FACTS.ANON::MOVIE-0000 :DIRECTOR "Ridley Scott"
FACTS.ANON::MOVIE-0000 :IS-A :MOVIE
FACTS.ANON::MOVIE-0000 :TITLE "Blade Runner"
FACTS.ANON::MOVIE-0001 :DIRECTOR "David Hand"
FACTS.ANON::MOVIE-0001 :DIRECTOR "William Cottrell"
FACTS.ANON::MOVIE-0001 :IS-A :MOVIE
FACTS.ANON::MOVIE-0001 :TITLE "Snow White"
=> NIL
The second version with ?movie will generate an anonymous symbol prefixed with movie-.
It is considered a more clean and efficient way to abstract identifiers.
FACTS:RM &rest SPECS
(facts:rm (?movie :actor "Harison Ford"))
FACTS:WITH SPECS &body BODY
To follow Wittgenstein’s view of the world, all queries get turned into testing the presence or absence of triples (facts).
Variables are prefixed with a question mark symbol “?” and are wildcards, matching everything. Nested queries get their variables expanded, giving pattern matching abilities. For instance :
(with ((?s ?p ?o)
(format t "~&~S ~S ~S~&" ?s ?p ?o))
=>
"Blade Runner" :ACTOR "Harison Ford"
"Blade Runner" :ACTOR "Rutger Hauer"
"Blade Runner" :DIRECTOR "Ridley Scott"
"Blade Runner" :IS-A :MOVIE
"Snow White" :DIRECTOR "David Hand"
"Snow White" :DIRECTOR "William Cottrell"
"Snow White" :IS-A :MOVIE
Multiple queries on the same subject can be grouped together easily :
(facts:with ((?movie :is-a :movie
:title ?title
:director ?director))
(format t "~A directed ~A~%" ?director ?title))
Ridley Scott directed Blade Runner
David Hand directed Snow White and the Seven Dwarfs
William Cottrell directed Snow White and the Seven Dwarfs
=> (values)
Negative facts specifications will remove matching facts from the results.
(with ((?s ?p ?o)
(:not ?s :actor "Harison Ford"))
(format t "~&~S ~S ~S~&" ?s ?p ?o))
=>
"Snow White" :DIRECTOR "David Hand"
"Snow White" :DIRECTOR "William Cottrell"
"Snow White" :IS-A :MOVIE
FACTS:*DB*
The current facts database.
FACTS:CLEAR-DB
Clears the database from every facts.
FACTS:SAVE-DB &key INTO (READABLY T)
Dump the database facts into filespec INTO.
FACTS:LOAD-DB SRC
Load the facts from SRC into *db*.
FACTS:WITH-TRANSACTION &body BODY
Enclose BODY database operations into a transaction.
A transaction ensures that all database operations will succeed or be reverted using their respective rollback functions.
Transactions can be nested safely.
TODO
- binding of negation : :not resulting from another binding
- barriers / hooks : functions that will be called when a spec is added or removed.
Source
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README.md
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facts-db/cl-facts ================= > 1.1 The world is the totality of facts, not of things. > > -- Ludwig Wittgenstein, Tractatus Logico Philosophicus cl-facts is a small in-memory graph database for Common Lisp. It features : * a triple store based on unlabelled skip lists * a very simple query language (facts:with) * transactions using rollback functions * logging and replay of transactions to/from disk * dumping and loading the database to/from disk --- Requirements ------------ You will need : * https://git.kmx.io/facts-db/cl-compare * https://git.kmx.io/facts-db/cl-rollback --- Usage ----- ### FACTS:ADD &rest SPECS Adds facts (triples) to the database. Triples can be grouped by subject. ```common-lisp (facts:add ("Blade Runner" :is-a :movie :director "Ridley Scott" :actor "Harison Ford" :actor "Rutger Hauer") ("Snow White" :is-a :movie :director "William Cottrell" :director "David Hand")) ``` or either ```common-lisp (facts:add (?movie :is-a :movie :title "Blade Runner" :director "Ridley Scott" :actor "Harrison Ford" :actor "Rutger Hauer")) (facts:add (?movie :is-a :movie :title "Snow White and the Seven Dwarfs" :director "William Cottrell" :director "David Hand")) (with ((?s ?p ?o)) (format t "~&~S ~S ~S~&" ?s ?p ?o)) FACTS.ANON::MOVIE-0000 :ACTOR "Harison Ford" FACTS.ANON::MOVIE-0000 :ACTOR "Rutger Hauer" FACTS.ANON::MOVIE-0000 :DIRECTOR "Ridley Scott" FACTS.ANON::MOVIE-0000 :IS-A :MOVIE FACTS.ANON::MOVIE-0000 :TITLE "Blade Runner" FACTS.ANON::MOVIE-0001 :DIRECTOR "David Hand" FACTS.ANON::MOVIE-0001 :DIRECTOR "William Cottrell" FACTS.ANON::MOVIE-0001 :IS-A :MOVIE FACTS.ANON::MOVIE-0001 :TITLE "Snow White" => NIL ``` The second version with `?movie` will generate an anonymous symbol prefixed with `movie-`. It is considered a more clean and efficient way to abstract identifiers. --- ### FACTS:RM &rest SPECS ```common-lisp (facts:rm (?movie :actor "Harison Ford")) ``` --- ### FACTS:WITH SPECS &body BODY To follow Wittgenstein's view of the world, all queries get turned into testing the presence or absence of triples (facts). Variables are prefixed with a question mark symbol "?" and are wildcards, matching everything. Nested queries get their variables expanded, giving pattern matching abilities. For instance : ```common-lisp (with ((?s ?p ?o) (format t "~&~S ~S ~S~&" ?s ?p ?o)) => "Blade Runner" :ACTOR "Harison Ford" "Blade Runner" :ACTOR "Rutger Hauer" "Blade Runner" :DIRECTOR "Ridley Scott" "Blade Runner" :IS-A :MOVIE "Snow White" :DIRECTOR "David Hand" "Snow White" :DIRECTOR "William Cottrell" "Snow White" :IS-A :MOVIE ``` Multiple queries on the same subject can be grouped together easily : ```common-lisp (facts:with ((?movie :is-a :movie :title ?title :director ?director)) (format t "~A directed ~A~%" ?director ?title)) Ridley Scott directed Blade Runner David Hand directed Snow White and the Seven Dwarfs William Cottrell directed Snow White and the Seven Dwarfs => (values) ``` Negative facts specifications will remove matching facts from the results. ```common-lisp (with ((?s ?p ?o) (:not ?s :actor "Harison Ford")) (format t "~&~S ~S ~S~&" ?s ?p ?o)) => "Snow White" :DIRECTOR "David Hand" "Snow White" :DIRECTOR "William Cottrell" "Snow White" :IS-A :MOVIE ``` --- ### FACTS:\*DB\* The current facts database. --- ### FACTS:CLEAR-DB Clears the database from every facts. --- ### FACTS:SAVE-DB &key INTO (READABLY T) Dump the database facts into filespec INTO. --- ### FACTS:LOAD-DB SRC Load the facts from SRC into \*db\*. --- ### FACTS:WITH-TRANSACTION &body BODY Enclose BODY database operations into a transaction. A transaction ensures that all database operations will succeed or be reverted using their respective rollback functions. Transactions can be nested safely. --- TODO ---- - binding of negation : :not resulting from another binding - barriers / hooks : functions that will be called when a spec is added or removed.