factor/extra/logic/logic.factor

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Factor

! Copyright (C) 2019-2020 KUSUMOTO Norio.
! See http://factorcode.org/license.txt for BSD license.
USING: accessors arrays assocs classes classes.tuple combinators
combinators.short-circuit compiler.units continuations
formatting fry io kernel lexer lists locals make math multiline
namespaces parser prettyprint prettyprint.backend
prettyprint.config prettyprint.custom prettyprint.sections
quotations sequences sequences.deep sequences.generalizations
sets splitting strings vectors words words.symbol ;
IN: logic
SYMBOL: !! ! cut operator in prolog: !
SYMBOL: __ ! anonymous variable in prolog: _
SYMBOL: ;; ! disjunction, or in prolog: ;
SYMBOL: \+ ! negation in prolog: not, \+
<PRIVATE
<<
TUPLE: logic-pred name defs ;
: <pred> ( name -- pred )
logic-pred new
swap >>name
V{ } clone >>defs ;
MIXIN: LOGIC-VAR
SINGLETON: NORMAL-LOGIC-VAR
SINGLETON: ANONYMOUSE-LOGIC-VAR
INSTANCE: NORMAL-LOGIC-VAR LOGIC-VAR
INSTANCE: ANONYMOUSE-LOGIC-VAR LOGIC-VAR
: logic-var? ( obj -- ? )
dup symbol? [ get LOGIC-VAR? ] [ drop f ] if ; inline
SYMBOLS: *trace?* *trace-depth* ;
: define-logic-var ( name -- )
create-word-in
[ reset-generic ]
[ define-symbol ]
[ NORMAL-LOGIC-VAR swap set-global ] tri ;
: define-logic-pred ( name -- )
create-word-in
[ reset-generic ]
[ define-symbol ]
[ [ name>> <pred> ] keep set-global ] tri ;
PRIVATE>
: trace ( -- ) t *trace?* set-global ;
: notrace ( -- ) f *trace?* set-global ;
SYNTAX: LOGIC-VAR: scan-token define-logic-var ;
SYNTAX: LOGIC-VARS: ";" [ define-logic-var ] each-token ;
SYNTAX: LOGIC-PRED: scan-token define-logic-pred ;
SYNTAX: LOGIC-PREDS: ";" [ define-logic-pred ] each-token ;
>>
SYNTAX: %!
"!%" parse-multiline-string drop ;
<PRIVATE
TUPLE: logic-goal pred args ;
: called-args ( args -- args' )
[ dup callable? [ call( -- term ) ] when ] map ; inline
:: <goal> ( pred args -- goal )
pred get args called-args logic-goal boa ; inline
: def>goal ( goal-def -- goal ) unclip swap <goal> ;
: normalize ( goal-def/defs -- goal-defs )
dup {
[ !! = ]
[ ?first dup symbol? [ get logic-pred? ] [ drop f ] if ]
} 1|| [ 1array ] when ;
TUPLE: logic-env table ;
: <env> ( -- env ) logic-env new H{ } clone >>table ; inline
:: env-put ( x pair env -- ) pair x env table>> set-at ; inline
: env-get ( x env -- pair/f ) table>> at ; inline
: env-delete ( x env -- ) table>> delete-at ; inline
: env-clear ( env -- ) table>> clear-assoc ; inline
: dereference ( term env -- term' env' )
[ 2dup env-get [ 2nip first2 t ] [ f ] if* ] loop ; inline
PRIVATE>
M: logic-env at*
dereference {
{ [ over logic-goal? ] [
[ [ pred>> ] [ args>> ] bi ] dip at <goal> t ] }
{ [ over tuple? ] [
'[ tuple-slots [ _ at ] map ]
[ class-of slots>tuple ] bi t ] }
{ [ over sequence? ] [
'[ _ at ] map t ] }
[ drop t ]
} cond ; inline
<PRIVATE
TUPLE: callback-env env trail ;
C: <callback-env> callback-env inline
M: callback-env at* env>> at* ; inline
TUPLE: cut-info cut? ;
C: <cut> cut-info inline
: cut? ( cut-info -- ? ) cut?>> ; inline
: set-info ( ? cut-info -- ) cut?<< ; inline
: set-info-if-f ( ? cut-info -- )
dup cut?>> [ 2drop ] [ cut?<< ] if ; inline
: 2each-until ( seq1 seq2 quot -- all-failed? ) 2 nfind 2drop f = ; inline
DEFER: unify*
:: (unify*) ( x! x-env! y! y-env! trail tmp-env -- success? )
f :> ret-value! f :> ret?! f :> ret2?!
[
{
{ [ x logic-var? ] [
x x-env env-get :> xp
xp [
xp first2 x-env! x!
x x-env dereference x-env! x!
t
] [
y y-env dereference y-env! y!
x y = x-env y-env eq? and [
x { y y-env } x-env env-put
x-env tmp-env eq? [
{ x x-env } trail push
] unless
] unless
t ret?! t ret-value!
f
] if ] }
{ [ y logic-var? ] [
x y x! y! x-env y-env x-env! y-env!
t ] }
[ f ]
} cond
] loop
ret? [
t ret-value!
x y [ logic-goal? ] both? [
x pred>> y pred>> = [
x args>> x! y args>> y!
] [
f ret-value! t ret2?!
] if
] when
ret2? [
{
{ [ x y [ tuple? ] both? ] [
x y [ class-of ] same? [
x y [ tuple-slots ] bi@ [| x-item y-item |
x-item x-env y-item y-env trail tmp-env unify* not
] 2each-until
] [ f ] if ret-value! ] }
{ [ x y [ sequence? ] both? ] [
x y [ class-of ] same? x y [ length ] same? and [
x y [| x-item y-item |
x-item x-env y-item y-env trail tmp-env unify* not
] 2each-until
] [ f ] if ret-value! ] }
[ x y = ret-value! ]
} cond
] unless
] unless
ret-value ;
:: unify* ( x x-env y y-env trail tmp-env -- success? )
*trace?* get-global :> trace?
0 :> depth!
trace? [
*trace-depth* counter depth!
depth [ "\t" printf ] times
"Unification of " printf x-env x of pprint
" and " printf y pprint nl
] when
x x-env y y-env trail tmp-env (unify*) :> success?
trace? [
depth [ "\t" printf ] times
success? [ "==> Success\n" ] [ "==> Fail\n" ] if "%s\n" printf
*trace-depth* get-global 1 - *trace-depth* set-global
] when
success? ; inline
SYMBOLS:
s-start:
s-not-empty:
s-cut: s-cut/iter:
s-not-cut:
s-defs-loop:
s-callable: s-callable/iter:
s-not-callable: s-not-callable/outer-iter: s-not-callable/inner-iter:
s-unify?-exit:
s-defs-loop-end:
s-end: ;
TUPLE: resolver-gen
{ state initial: s-start: }
body env cut
first-goal rest-goals d-head d-body defs trail d-env d-cut
sub-resolver1 sub-resolver2 i loop-end
yield? return? ;
:: <resolver> ( body env cut -- resolver )
resolver-gen new
body >>body env >>env cut >>cut ; inline
GENERIC: next ( generator -- yield? )
M:: resolver-gen next ( resolver -- yield? )
[
f resolver return?<<
f resolver yield?<<
resolver state>> {
{ s-start: [
resolver body>> empty? [
t resolver yield?<<
s-end: resolver state<<
] [
s-not-empty: resolver state<<
] if ] }
{ s-not-empty: [
resolver body>> unclip
[ resolver rest-goals<< ] [ resolver first-goal<< ] bi*
resolver first-goal>> !! = [ ! cut
s-cut: resolver state<<
] [
s-not-cut: resolver state<<
] if ] }
{ s-cut: [
resolver [ rest-goals>> ] [ env>> ] [ cut>> ] tri <resolver>
resolver sub-resolver1<<
s-cut/iter: resolver state<< ] }
{ s-cut/iter: [
resolver sub-resolver1>> next [
t resolver yield?<<
] [
t resolver cut>> set-info
s-end: resolver state<<
] if ] }
{ s-not-cut: [
resolver first-goal>> callable? [
resolver first-goal>> call( -- goal ) resolver first-goal<<
] when
*trace?* get-global [
resolver first-goal>>
[ pred>> name>> "in: { %s " printf ]
[ args>> [ "%u " printf ] each "}\n" printf ] bi
] when
<env> resolver d-env<<
f <cut> resolver d-cut<<
resolver first-goal>> pred>> defs>> dup resolver defs<<
length 1 - dup 0 >= [
resolver loop-end<<
0 resolver i<<
s-defs-loop: resolver state<<
] [
drop
s-end: resolver state<<
] if ] }
{ s-defs-loop: [
resolver [ i>> ] [ defs>> ] bi nth
first2 [ resolver d-head<< ] [ resolver d-body<< ] bi*
resolver d-cut>> cut? resolver cut>> cut? or [
s-end: resolver state<<
] [
V{ } clone resolver trail<<
resolver {
[ first-goal>> ]
[ env>> ]
[ d-head>> ]
[ d-env>> ]
[ trail>> ]
[ d-env>> ]
} cleave unify* [
resolver d-body>> callable? [
s-callable: resolver state<<
] [
s-not-callable: resolver state<<
] if
] [
s-unify?-exit: resolver state<<
] if
] if ] }
{ s-callable: [
resolver [ d-env>> ] [ trail>> ] bi <callback-env>
resolver d-body>> call( cb-env -- ? ) [
resolver [ rest-goals>> ] [ env>> ] [ cut>> ] tri <resolver>
resolver sub-resolver1<<
s-callable/iter: resolver state<<
] [
s-unify?-exit: resolver state<<
] if ] }
{ s-callable/iter: [
resolver sub-resolver1>> next [
t resolver yield?<<
] [
s-unify?-exit: resolver state<<
] if ] }
{ s-not-callable: [
resolver [ d-body>> ] [ d-env>> ] [ d-cut>> ] tri <resolver>
resolver sub-resolver1<<
s-not-callable/outer-iter: resolver state<< ] }
{ s-not-callable/outer-iter: [
resolver sub-resolver1>> next [
resolver [ rest-goals>> ] [ env>> ] [ cut>> ] tri <resolver>
resolver sub-resolver2<<
s-not-callable/inner-iter: resolver state<<
] [
s-unify?-exit: resolver state<<
] if ] }
{ s-not-callable/inner-iter: [
resolver sub-resolver2>> next [
t resolver yield?<<
] [
resolver cut>> cut? resolver d-cut>> set-info-if-f
s-not-callable/outer-iter: resolver state<<
] if ] }
{ s-unify?-exit: [
resolver trail>> [ first2 env-delete ] each
resolver d-env>> env-clear
s-defs-loop-end: resolver state<< ] }
{ s-defs-loop-end: [
resolver [ i>> ] [ loop-end>> ] bi >= [
s-end: resolver state<<
] [
resolver [ 1 + ] change-i drop
s-defs-loop: resolver state<<
] if ] }
{ s-end: [
t resolver return?<< ] }
} case
resolver [ yield?>> ] [ return?>> ] bi or not
] loop
resolver yield?>> ;
: split-body ( body -- bodies ) { ;; } split [ >array ] map ;
SYMBOL: *anonymouse-var-no*
: reset-anonymouse-var-no ( -- ) 0 *anonymouse-var-no* set-global ;
: proxy-var-for-'__' ( -- var-symbol )
[
*anonymouse-var-no* counter "ANON-%d_" sprintf
"logic.private" create-word dup dup
define-symbol
ANONYMOUSE-LOGIC-VAR swap set-global
] with-compilation-unit ;
: replace-'__' ( before -- after )
{
{ [ dup __ = ] [ drop proxy-var-for-'__' ] }
{ [ dup sequence? ] [ [ replace-'__' ] map ] }
{ [ dup tuple? ] [
[ tuple-slots [ replace-'__' ] map ]
[ class-of slots>tuple ] bi ] }
[ ]
} cond ;
: collect-logic-vars ( seq -- vars-array )
[ logic-var? ] deep-filter members ;
SYMBOL: dummy-item
:: negation-goal ( goal -- negation-goal )
"failo_" <pred> :> f-pred
f-pred { } clone logic-goal boa :> f-goal
V{ { f-goal [ drop f ] } } f-pred defs<<
goal pred>> name>> "\\+%s_" sprintf <pred> :> negation-pred
negation-pred goal args>> clone logic-goal boa :> negation-goal
V{
{ negation-goal { goal !! f-goal } } ! \+P_ { P !! { failo_ } } rule
{ negation-goal { } } ! \+P_ fact
} negation-pred defs<<
negation-goal ;
SYMBOLS: at-the-beginning at-the-end ;
:: (rule) ( head body pos -- )
reset-anonymouse-var-no
head replace-'__' def>goal :> head-goal
body replace-'__' normalize
split-body pos at-the-beginning = [ reverse ] when ! disjunction
dup empty? [
head-goal swap 2array 1vector
head-goal pred>> [
pos at-the-end = [ swap ] when append!
] change-defs drop
] [
f :> negation?!
[
[
{
{ [ dup \+ = ] [ drop dummy-item t negation?! ] }
{ [ dup array? ] [
def>goal negation? [ negation-goal ] when
f negation?! ] }
{ [ dup callable? ] [
call( -- goal ) negation? [ negation-goal ] when
f negation?! ] }
{ [ dup [ t = ] [ f = ] bi or ] [
:> t/f! negation? [ t/f not t/f! ] when
t/f "trueo_" "failo_" ? <pred> :> t/f-pred
t/f-pred { } clone logic-goal boa :> t/f-goal
V{ { t/f-goal [ drop t/f ] } } t/f-pred defs<<
t/f-goal
f negation?! ] }
{ [ dup !! = ] [ f negation?! ] } ! as '!!'
[ drop dummy-item f negation?! ]
} cond
] map dummy-item swap remove :> body-goals
V{ { head-goal body-goals } }
head-goal pred>> [
pos at-the-end = [ swap ] when append!
] change-defs drop
] each
] if ;
: (fact) ( head pos -- ) { } clone swap (rule) ;
PRIVATE>
: rule ( head body -- ) at-the-end (rule) ;
: rule* ( head body -- ) at-the-beginning (rule) ;
: rules ( defs -- ) [ first2 rule ] each ;
: fact ( head -- ) at-the-end (fact) ;
: fact* ( head -- ) at-the-beginning (fact) ;
: facts ( defs -- ) [ fact ] each ;
:: callback ( head quot: ( callback-env -- ? ) -- )
head def>goal :> head-goal
head-goal pred>> [
{ head-goal quot } suffix!
] change-defs drop ;
: callbacks ( defs -- ) [ first2 callback ] each ; inline
:: retract ( head-def -- )
head-def replace-'__' def>goal :> head-goal
head-goal pred>> defs>> :> defs
defs [ first <env> head-goal <env> V{ } clone <env> (unify*) ] find [
head-goal pred>> [ remove-nth! ] change-defs drop
] [ drop ] if ;
:: retract-all ( head-def -- )
head-def replace-'__' def>goal :> head-goal
head-goal pred>> defs>> :> defs
defs [
first <env> head-goal <env> V{ } clone <env> (unify*)
] reject! head-goal pred>> defs<< ;
: clear-pred ( pred -- ) get V{ } clone swap defs<< ;
:: unify ( cb-env x y -- success? )
cb-env env>> :> env
x env y env cb-env trail>> env (unify*) ;
:: is ( quot: ( env -- value ) dist -- goal )
quot collect-logic-vars
dup dist swap member? [ dist suffix ] unless :> args
quot dist "[ %u %s is ]" sprintf <pred> :> is-pred
is-pred args logic-goal boa :> is-goal
V{
{
is-goal
[| env | env dist env quot call( env -- value ) unify ]
}
} is-pred defs<<
is-goal ;
:: =:= ( quot: ( env -- n m ) -- goal )
quot collect-logic-vars :> args
quot "[ %u =:= ]" sprintf <pred> :> =:=-pred
=:=-pred args logic-goal boa :> =:=-goal
V{
{
=:=-goal
[| env |
env quot call( env -- n m )
2dup [ number? ] both? [ = ] [ 2drop f ] if ]
}
} =:=-pred defs<<
=:=-goal ;
:: =\= ( quot: ( env -- n m ) -- goal )
quot collect-logic-vars :> args
quot "[ %u =\\= ]" sprintf <pred> :> =\=-pred
=\=-pred args logic-goal boa :> =\=-goal
V{
{
=\=-goal
[| env |
env quot call( env -- n m )
2dup [ number? ] both? [ = not ] [ 2drop f ] if ]
}
} =\=-pred defs<<
=\=-goal ;
:: invoke ( quot: ( env -- ) -- goal )
quot collect-logic-vars :> args
quot "[ %u invoke ]" sprintf <pred> :> invoke-pred
invoke-pred args logic-goal boa :> invoke-goal
V{
{ invoke-goal [| env | env quot call( env -- ) t ] }
} invoke-pred defs<<
invoke-goal ;
:: invoke* ( quot: ( env -- ? ) -- goal )
quot collect-logic-vars :> args
quot "[ %u invoke* ]" sprintf <pred> :> invoke*-pred
invoke*-pred args logic-goal boa :> invoke*-goal
V{
{ invoke*-goal [| env | env quot call( env -- ? ) ] }
} invoke*-pred defs<<
invoke*-goal ;
:: nquery ( goal-def/defs n/f -- bindings-array/success? )
*trace?* get-global :> trace?
0 :> n!
f :> success?!
V{ } clone :> bindings
<env> :> env
goal-def/defs replace-'__' normalize [ def>goal ] map
env f <cut>
<resolver> :> resolver
[
[
resolver next dup [
resolver env>> table>> keys [ get NORMAL-LOGIC-VAR? ] filter
[ dup env at ] H{ } map>assoc
trace? get-global [ dup [ "%u: %u\n" printf ] assoc-each ] when
bindings push
t success?!
n/f [
n 1 + n!
n n/f >= [ return ] when
] when
] when
] loop
] with-return
bindings dup {
[ empty? ]
[ first keys empty? ]
} 1|| [ drop success? ] [ >array ] if ;
: query ( goal-def/defs -- bindings-array/success? ) f nquery ;
! nquery has been modified to use generators created by finite
! state machines to reduce stack consumption.
! Since the processing algorithm of the code is difficult
! to understand, the words no longer used are kept as private
! words for verification.
<PRIVATE
: each-until ( seq quot -- ) find 2drop ; inline
:: resolve-body ( body env cut quot: ( -- ) -- )
body empty? [
quot call( -- )
] [
body unclip :> ( rest-goals! first-goal! )
first-goal !! = [ ! cut
rest-goals env cut quot resolve-body
t cut set-info
] [
first-goal callable? [
first-goal call( -- goal ) first-goal!
] when
*trace?* get-global [
first-goal
[ pred>> name>> "in: { %s " printf ]
[ args>> [ "%u " printf ] each "}\n" printf ] bi
] when
<env> :> d-env!
f <cut> :> d-cut!
first-goal pred>> defs>> [
first2 :> ( d-head d-body )
first-goal d-head [ args>> length ] same? [
d-cut cut? cut cut? or [ t ] [
V{ } clone :> trail
first-goal env d-head d-env trail d-env unify* [
d-body callable? [
d-env trail <callback-env> d-body call( cb-env -- ? ) [
rest-goals env cut quot resolve-body
] when
] [
d-body d-env d-cut [
rest-goals env cut quot resolve-body
cut cut? d-cut set-info-if-f
] resolve-body
] if
] when
trail [ first2 env-delete ] each
d-env env-clear
f
] if
] [ f ] if
] each-until
] if
] if ;
:: (resolve) ( goal-def/defs quot: ( env -- ) -- )
goal-def/defs replace-'__' normalize [ def>goal ] map :> goals
<env> :> env
goals env f <cut> [ env quot call( env -- ) ] resolve-body ;
: resolve ( goal-def/defs quot: ( env -- ) -- ) (resolve) ;
:: nquery/rec ( goal-def/defs n/f -- bindings-array/success? )
*trace?* get-global :> trace?
0 :> n!
f :> success?!
V{ } clone :> bindings
[
goal-def/defs normalize [| env |
env table>> keys [ get NORMAL-LOGIC-VAR? ] filter
[ dup env at ] H{ } map>assoc
trace? get-global [ dup [ "%u: %u\n" printf ] assoc-each ] when
bindings push
t success?!
n/f [
n 1 + n!
n n/f >= [ return ] when
] when
] (resolve)
] with-return
bindings dup {
[ empty? ]
[ first keys empty? ]
} 1|| [ drop success? ] [ >array ] if ;
: query/rec ( goal-def/defs -- bindings-array/success? )
f nquery/rec ;
PRIVATE>
! Built-in predicate definitions -----------------------------------------------------
LOGIC-PREDS:
trueo failo
varo nonvaro
(<) (>) (>=) (=<) (==) (\==) (=) (\=)
writeo writenlo nlo
membero appendo lengtho listo ;
{ trueo } [ drop t ] callback
{ failo } [ drop f ] callback
<PRIVATE LOGIC-VARS: X Y Z ; PRIVATE>
{ varo X } [ X of logic-var? ] callback
{ nonvaro X } [ X of logic-var? not ] callback
{ (<) X Y } [
[ X of ] [ Y of ] bi 2dup [ number? ] both? [ < ] [ 2drop f ] if
] callback
{ (>) X Y } [
[ X of ] [ Y of ] bi 2dup [ number? ] both? [ > ] [ 2drop f ] if
] callback
{ (>=) X Y } [
[ X of ] [ Y of ] bi 2dup [ number? ] both? [ >= ] [ 2drop f ] if
] callback
{ (=<) X Y } [
[ X of ] [ Y of ] bi 2dup [ number? ] both? [ <= ] [ 2drop f ] if
] callback
{ (==) X Y } [ [ X of ] [ Y of ] bi = ] callback
{ (\==) X Y } [ [ X of ] [ Y of ] bi = not ] callback
{ (=) X Y } [ dup [ X of ] [ Y of ] bi unify ] callback
{ (\=) X Y } [
clone [ clone ] change-env [ clone ] change-trail
dup [ X of ] [ Y of ] bi unify not
] callback
{ writeo X } [
X of dup sequence? [
[ dup string? [ printf ] [ pprint ] if ] each
] [
dup string? [ printf ] [ pprint ] if
] if t
] callback
{ writenlo X } [
X of dup sequence? [
[ dup string? [ printf ] [ pprint ] if ] each
] [
dup string? [ printf ] [ pprint ] if
] if nl t
] callback
{ nlo } [ drop nl t ] callback
<PRIVATE LOGIC-VARS: L L1 L2 L3 Head Tail N N1 ; PRIVATE>
{ membero X L{ X . Tail } } fact
{ membero X L{ Head . Tail } } { membero X Tail } rule
{ appendo L{ } L L } fact
{ appendo L{ X . L1 } L2 L{ X . L3 } } {
{ appendo L1 L2 L3 }
} rule
{ lengtho L{ } 0 } fact
{ lengtho L{ __ . Tail } N } {
{ lengtho Tail N1 }
[ [ N1 of 1 + ] N is ]
} rule
{ listo L{ } } fact
{ listo L{ __ . __ } } fact