| Title: | Query 'SWI'-'Prolog' from R |
|---|---|
| Description: | This R package connects to SWI-Prolog, <https://www.swi-prolog.org/>, so that R can send deterministic and non-deterministic queries to prolog (consult, query/submit, once, findall). |
| Authors: | Matthias Gondan [aut, com, cre] (University of Innsbruck), European Commission [fnd] (Erasmus+ Programme, 2019-1-EE01-KA203-051708) |
| Maintainer: | Matthias Gondan <[email protected]> |
| License: | FreeBSD |
| Version: | 0.9.21 |
| Built: | 2025-03-11 10:21:50 UTC |
| Source: | https://github.com/mgondan/rolog |
Translate simplified to canonical representation
as.rolog(query = quote(member(.X, ""[a, "b", 3L, 4, (pi), TRUE, .Y])))as.rolog(query = quote(member(.X, ""[a, "b", 3L, 4, (pi), TRUE, .Y])))
query |
an R call representing a Prolog query with prolog-like syntax, e.g., 'member(.X, ""[a, b, .Y])' for use in [query()], [once()], and [findall()]. The argument is translated to Rolog's representation, with R calls corresponding to Prolog terms and R expressions corresponding to Prolog variables. Variables and expressions in parentheses are evaluated. |
[query()], [once()], [findall()]
q <- quote(member(.X, ""[a, "b", 3L, 4, pi, (pi), TRUE, .Y])) as.rolog(q) q <- quote(member(.X, ""[a, "b", 3L, 4, pi, (pi), TRUE, .Y])) findall(as.rolog(q))q <- quote(member(.X, ""[a, "b", 3L, 4, pi, (pi), TRUE, .Y])) as.rolog(q) q <- quote(member(.X, ""[a, "b", 3L, 4, pi, (pi), TRUE, .Y])) findall(as.rolog(q))
Clear current query
clear()clear()
TRUE (invisible)
query()
for a opening a query.
submit()
for a submitting a query.
once()
for a opening a query, submitting it, and clearing it again.
findall()
for a opening a query, collecting all solutions, and clearing it again.
query(call("member", expression(X), list(quote(a), "b", 3L, 4))) submit() # X = a submit() # X = "b" clear()query(call("member", expression(X), list(quote(a), "b", 3L, 4))) submit() # X = a submit() # X = "b" clear()
Consult a prolog database
consult(fname = system.file(file.path("pl", "family.pl"), package = "rolog"))consult(fname = system.file(file.path("pl", "family.pl"), package = "rolog"))
fname |
file name of database |
TRUE on success
once(), findall(), and query()/submit()/clear() for executing queries
consult(fname=system.file(file.path("pl", "family.pl"), package="rolog")) findall(call("ancestor", quote(pam), expression(X)))consult(fname=system.file(file.path("pl", "family.pl"), package="rolog")) findall(call("ancestor", quote(pam), expression(X)))
Invoke a query several times
findall( query = call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, expression(Y))), options = list(portray = FALSE), env = globalenv() )findall( query = call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, expression(Y))), options = list(portray = FALSE), env = globalenv() )
query |
an R call. The R call consists of symbols, integers and real numbers, character strings, boolean values, expressions, lists, and other calls. Vectors of booleans, integers, floating point numbers, and strings with length N > 1 are translated to prolog compounds !/N, %/N, #/N and $$/N, respectively. The names can be modified with the options below. |
options |
This is a list of options controlling translation from and to prolog.
|
env |
The R environment in which the query is run (default: globalenv()). This is mostly relevant for r_eval/2. |
If the query fails, an empty list is returned. If the query
succeeds N >= 1 times, a list of length N is returned, each element
being a list of conditions for each solution, see once().
once()
for a single query
query(), submit(), and clear() for fine-grained control over
non-deterministic queries
# This query returns a list stating that it works if X = a, "b", ... findall(call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, NULL, NA))) # Continued findall(call("member", expression(X), list(call("sin", call("/", quote(pi), 2)), expression(Y)))) # The same using simplified syntax q <- quote(member(.X, ""[a, "b", 3L, 4, TRUE, NULL, NA, sin(pi/2), .Y])) findall(as.rolog(q))# This query returns a list stating that it works if X = a, "b", ... findall(call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, NULL, NA))) # Continued findall(call("member", expression(X), list(call("sin", call("/", quote(pi), 2)), expression(Y)))) # The same using simplified syntax q <- quote(member(.X, ""[a, "b", 3L, 4, TRUE, NULL, NA, sin(pi/2), .Y])) findall(as.rolog(q))
Invoke a query once
once( query = call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, expression(Y))), options = list(portray = FALSE), env = globalenv() )once( query = call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, expression(Y))), options = list(portray = FALSE), env = globalenv() )
query |
an R call. The R call consists of symbols, integers and real numbers, character strings, boolean values, expressions, lists, and other calls. Vectors of booleans, integers, floating point numbers, and strings with length N > 1 are translated to prolog compounds !/N, %/N, #/N and $$/N, respectively. The names can be modified with the options below. |
options |
This is a list of options controlling translation from and to prolog.
|
env |
The R environment in which the query is run (default: globalenv()). This is mostly relevant for r_eval/2. |
If the query fails, FALSE is returned. If the query succeeds, a
(possibly empty) list is returned that includes the bindings required to
satisfy the query.
findall()
for querying all solutions
query(), submit(), and clear() for fine-grained control over
non-deterministic queries
rolog_options()
for options controlling R to prolog translation
# This query returns FALSE once(call("member", 1, list(quote(a), quote(b), quote(c)))) # This query returns an empty list meaning yes, it works once(call("member", 3, list(1, 2, 3))) # This query returns a list stating that it works if X = 1 once(call("member", 1, list(quote(a), expression(X)))) # The same query using simplified syntax q = quote(member(1, ""[a, .X])) once(as.rolog(q)) # This query returns a list stating that X = 1 and Z = expression(Y) once(call("=", list(expression(X), expression(Y)), list(1, expression(Z)))) # This works for X = [1 | _]; i.e. something like [|](1, expression(_6330)) once(call("member", 1, expression(X))) # This returns S = '1.0' (scalar) once(call("format", call("string", expression(S)), "~w", list(1)), options=list(scalar=TRUE)) # This returns S = '#(1.0)' (vector), because the 1 is translated to #(1.0). # To prevent "~w" from being translated to $$("~w"), it is given as an atom. once(call("format", call("string", expression(S)), as.symbol("~w"), list(1)), options=list(scalar=FALSE))# This query returns FALSE once(call("member", 1, list(quote(a), quote(b), quote(c)))) # This query returns an empty list meaning yes, it works once(call("member", 3, list(1, 2, 3))) # This query returns a list stating that it works if X = 1 once(call("member", 1, list(quote(a), expression(X)))) # The same query using simplified syntax q = quote(member(1, ""[a, .X])) once(as.rolog(q)) # This query returns a list stating that X = 1 and Z = expression(Y) once(call("=", list(expression(X), expression(Y)), list(1, expression(Z)))) # This works for X = [1 | _]; i.e. something like [|](1, expression(_6330)) once(call("member", 1, expression(X))) # This returns S = '1.0' (scalar) once(call("format", call("string", expression(S)), "~w", list(1)), options=list(scalar=TRUE)) # This returns S = '#(1.0)' (vector), because the 1 is translated to #(1.0). # To prevent "~w" from being translated to $$("~w"), it is given as an atom. once(call("format", call("string", expression(S)), as.symbol("~w"), list(1)), options=list(scalar=FALSE))
Translate an R call to a prolog compound and pretty print it
portray( query = call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, expression(Y))), options = NULL )portray( query = call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, expression(Y))), options = NULL )
query |
an R call. The R call consists of symbols, integers and real numbers, character strings, boolean values, expressions and lists, and other calls. Vectors of booleans, integers, floating point numbers, and strings with length N > 1 are translated to prolog compounds !/N, %/N, #/N and $$/N, respectively. The names can be modified with the options below. |
options |
This is a list of options controlling translation from and to prolog.
|
The R elements are translated to the following prolog citizens:
numeric -> real (vectors of size N -> #/N)
integer -> integer (vectors -> %/N)
character -> string (vectors -> $$/N)
symbol/name -> atom
expression -> variable
call/language -> compound
boolean -> true, false (atoms)
list -> list
character string with the prolog syntax of the call
rolog_options() for fine-grained control over the translation
Default hook for postprocessing
postproc(constraint = call("=<", 1, 2))postproc(constraint = call("=<", 1, 2))
constraint |
the R call representing constraints of the Prolog query. |
The default hook translates the inequality and smaller-than-or-equal-to back from Prolog (\=, =<) to R (!=, <=).
[rolog_options()] for fine-grained control over the translation
Default hook for preprocessing
preproc(query = quote(1 <= sin))preproc(query = quote(1 <= sin))
query |
the R call representing the Prolog query. |
The default hook translates the inequality and smaller-than-or-equal-to from R (!=, <=) to Prolog (\=, =<). Moreover, primitive functions are converted to regular functions.
[rolog_options()] for fine-grained control over the translation
Create a query
query( query = call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, expression(Y))), options = NULL, env = globalenv() )query( query = call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, expression(Y))), options = NULL, env = globalenv() )
query |
an R call. The R call consists of symbols, integers and real numbers, character strings, boolean values, expressions, lists, and other calls. Vectors of booleans, integers, floating point numbers, and strings with length N > 1 are translated to prolog compounds !/N, %/N, #/N and $$/N, respectively. The names can be modified with the options below. |
options |
This is a list of options controlling translation from and to prolog.
|
env |
The R environment in which the query is run (default: globalenv()). This is mostly relevant for r_eval/2. |
SWI-Prolog does not allow multiple open queries. If another query is open, it it is closed and a warning is shown.
If the creation of the query succeeds, TRUE.
once() for a query that is submitted only a single time.
findall() for a query that is submitted until it fails.
query(call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, expression(Y)))) submit() # X = a submit() # X = "b" clear() query(call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, expression(Y), NA, NaN, Inf, NULL, function(x) {y <- sin(x); y^2}))) submit() # X = a submit() # X = "b" submit() # X = 3L submit() # X = 4.0 submit() # X = TRUE submit() # X = expression(Y) or Y = expression(X) submit() # X = NA submit() # X = NaN submit() # X = Inf submit() # X = NULL submit() # X = function(x) {y <- sin(x); y^2})) submit() # FALSE (no more results) submit() # warning that no query is open query(call("member", expression(X), list(quote(a), "b", 3L, 4))) query(call("member", expression(X), list(TRUE, expression(Y)))) # warning that another query is open clear()query(call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, expression(Y)))) submit() # X = a submit() # X = "b" clear() query(call("member", expression(X), list(quote(a), "b", 3L, 4, TRUE, expression(Y), NA, NaN, Inf, NULL, function(x) {y <- sin(x); y^2}))) submit() # X = a submit() # X = "b" submit() # X = 3L submit() # X = 4.0 submit() # X = TRUE submit() # X = expression(Y) or Y = expression(X) submit() # X = NA submit() # X = NaN submit() # X = Inf submit() # X = NULL submit() # X = function(x) {y <- sin(x); y^2})) submit() # FALSE (no more results) submit() # warning that no query is open query(call("member", expression(X), list(quote(a), "b", 3L, 4))) query(call("member", expression(X), list(TRUE, expression(Y)))) # warning that another query is open clear()
Clean up when detaching the library
rolog_done()rolog_done()
'TRUE' on success
Start prolog
rolog_init(argv1 = commandArgs()[1])rolog_init(argv1 = commandArgs()[1])
argv1 |
file name of the R executable |
SWI-prolog is automatically initialized when the rolog library is loaded, so this function is normally not directly invoked.
'TRUE' on success
Check if rolog is properly loaded
rolog_ok(warn = FALSE, stop = FALSE)rolog_ok(warn = FALSE, stop = FALSE)
warn |
raise a warning if problems occurred |
stop |
raise an error if problems occurred |
TRUE if rolog is properly loaded
Quick access the package options
rolog_options()rolog_options()
Translation from R to Prolog
numeric vector of size N -> realvec/N (default is ##)
integer vector of size N -> intvec/N (default is %%)
boolean vector of size N -> boolvec/N (default is !!)
character vector of size N -> charvec/N (default is $$)
scalar: if TRUE (default), translate R vectors of length 1 to scalars
portray: if TRUE (default) whether to return the prolog translation
as an attribute to the return value of once(), query() and findall()
list with some options for translating R expressions to prolog
query() before.Submit a query that has been opened with query() before.
submit(options = NULL)submit(options = NULL)
options |
This is a list of options controlling translation from and to Prolog. Here, only postproc is relevant. |
If the query fails, FALSE is returned. If the query succeeds, a
(possibly empty) list is returned that includes the bindings required to
satisfy the query.
query()
for a opening a query.
rolog_options()
for fine-grained control on the translation from R to Prolog and back.
clear()
for a clearing a query.
once()
for a opening a query, submitting it, and clearing it again.
findall()
for a opening a query, collecting all solutions, and clearing it again.
query(call("member", expression(X), list(quote(a), "b", 3L, 4, expression(Y)))) submit() # X = 3L submit() # X = 4.0 submit() # X = TRUE submit() # X = expression(Y) or Y = expression(X) submit() # FALSE submit() # warning that no query is open query(call("member", expression(X), list(quote(a), "b", 3L, 4))) submit() # X = a submit() # X = "b" clear()query(call("member", expression(X), list(quote(a), "b", 3L, 4, expression(Y)))) submit() # X = 3L submit() # X = 4.0 submit() # X = TRUE submit() # X = expression(Y) or Y = expression(X) submit() # FALSE submit() # warning that no query is open query(call("member", expression(X), list(quote(a), "b", 3L, 4))) submit() # X = a submit() # X = "b" clear()