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  • SWI-Prolog as an embedded application in VS2008 C++

    - by H.J. Miri
    I have a C++ application (prog.sln) which is my main program and I want to use Prolog as an embedded logic server (hanoi.pl) int main(int argc, char** argv) { putenv( "SWI_HOME_DIR=C:\\Program Files\\pl" ); argv[0] = "libpl.dll"; argv[1] = "-x"; argv[2] = "hanoi.pl"; argv[3] = NULL; PL_initialise(argc, argv); { fid_t fid = PL_open_foreign_frame(); predicate_t pred = PL_predicate( "hanoi", 1, "user" ); int rval = PL_call_predicate( NULL, PL_Q_NORMAL, pred, 3 ); qid_t qid = PL_open_query( NULL, PL_Q_NORMAL, pred, 3 ); while ( PL_next_solution(qid) ) return qid; PL_close_query(qid); PL_close_foreign_frame(fid); system("PAUSE"); } return 1; system("PAUSE"); } Here is my Prolog source code: :- use_module( library(shlib) ). hanoi( N ):- move( N, left, center, right ). move( 0, _, _, _ ):- !. move( N, A, B, C ):- M is N-1, move( M, A, C, B ), inform( A, B ), move( M, C, B, A ). inform( X, Y ):- write( 'move a disk from ' ), write( X ), write( ' to ' ), write( Y ), nl. I type at the command: plld -o hanoi prog.sln hanoi.pl But it doesn't compile. When I run my C++ app, it says: Undefined procedure: hanoi/1 What is missing/wrong in my code or at the prompt that prevents my C++ app from consulting Prolog? Appreciate any help/pointer.

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  • Consulting a Prolog Source Code from within a VS2008 Solution File

    - by Joshua Green
    I have a Prolog file (Hanoi.pl) containing the code for solving the Hanoi Towers puzzle: hanoi( N ):- move( N, left, middle, right ). move( 0, _, _, _ ):- !. move( N, A, B, C ):- M is N-1, move( M, A, C, B ), inform( A, B ), move( M, C, B, A ). inform( X, Y ):- write( 'move a disk from ' ), write( X ), write( ' to ' ), writeln( Y ). I also have a C++ file written in VS2008 IDE: #include <iostream> #include <string> #include <stdio.h> #include <stdlib.h> using namespace std; #include "SWI-cpp.h" #include "SWI-Prolog.h" predicate_t phanoi; term_t t0; int main(int argc, char** argv) { long n = 5; int rval; if ( !PL_initialise(1, argv) ) PL_halt(1); PL_put_integer( t0, n ); phanoi = PL_predicate( "hanoi", 1, NULL ); rval = PL_call_predicate( NULL, PL_Q_NORMAL, phanoi, t0 ); system( "PAUSE" ); } How can I consult my Prolog source code (Hanoi.pl) from within my C++ code? Not from the Command Prompt - from the code, something like include or consult or compile? It is located in the same folder as my cpp file. Thanks,

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  • Appending facts into an existing prolog file.

    - by vuj
    Hi, I'm having trouble inserting facts into an existing prolog file, without overwriting the original contents. Suppose I have a file test.pl: :- dynamic born/2. born(john,london). born(tim,manchester). If I load this in prolog, and I assert more facts: | ?- assert(born(laura,kent)). yes I'm aware I can save this by doing: |?- tell('test.pl'),listing(born/2),told. Which works but test.pl now only contains the facts, not the ":- dynamic born/2": born(john,london). born(tim,manchester). born(laura,kent). This is problematic because if I reload this file, I won't be able to insert anymore facts into test.pl because ":- dynamic born/2." doesn't exist anymore. I read somewhere that, I could do: append('test.pl'),listing(born/2),told. which should just append to the end of the file, however, I get the following error: ! Existence error in user:append/1 ! procedure user:append/1 does not exist ! goal: user:append('test.pl') Btw, I'm using Sicstus prolog. Does this make a difference? Thanks!

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  • Matching tuples in Prolog

    - by milosz
    Why does Prolog match (X, Xs) with a tuple containing more elements? An example: test2((X, Xs)) :- write(X), nl, test2(Xs). test2((X)) :- write(X), nl. test :- read(W), test2(W). ?- test. |: a, b(c), d(e(f)), g. a b(c) d(e(f)) g yes Actually this is what I want to achieve but it seems suspicious. Is there any other way to treat a conjunction of terms as a list in Prolog?

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  • tuProlog unknow behavior

    - by Josh Guzman
    I'm using tuProlog to integrate Prolog with Java, to do so I'v been defined a .pl file wich contains this code: go:-write('hello world!'),nl. In my Java File at NetBeans i Have a Main Class that invokes this: Prolog engine = new Prolog(); Theory theory = new Theory(new FileInputStream("facultad.pl")); try { engine.setTheory(theory); } catch (InvalidTheoryException ex) { } SolveInfo solution = engine.solve("go."); if (solution.isSuccess()) { System.out.println(solution.getSolution()); } This Code must returns 'hello world', but instead of that it answer 'go', any ideas about this erratic behavior ??

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  • Prolog .. Can i convert from a list of chars to a string or term in Prolog !!

    - by AhmadAssaf
    i use read_line_to_codes(Stream,Line) to read a line from a file .. first is there any way to read a line and assign it to a term in prolog ?? if not i managed to read a line and put it in this char list .. now this char list contains spaces .. which is bad .. so i want to convert it to a term or a string in prolog so that i can process it easier .. spaces cannot be atoms so thats a problem .. i appreciate the help !!

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  • Problem when reading backslash in Prolog

    - by Jerry
    I'm writing a lexer in Prolog which will be used as a part of functional language interpreter. Language spec allows expressions like for example let \x = x + 2; to occur. What I want lexer to do for such input is to "return": [tokLet, tokLambda, tokVar(x), tokEq, tokVar(x), tokPlus, tokNumber(2), tokSColon] and the problem is, that Prolog seems to ignore the \ character and "returns" the line written above except for tokLambda. One approach to solve this would be to somehow add second backslash before/after every occurrence of one in the program code (because everything works fine if I change the original input to let \\x = x + 2;) but I don't really like it. Any ideas?

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  • Prolog singleton variables in Python

    - by Rubens
    I'm working on a little set of scripts in python, and I came to this: line = "a b c d e f g" a, b, c, d, e, f, g = line.split() I'm quite aware of the fact that these are decisions taken during implementation, but shouldn't (or does) python offer something like: _, _, var_needed, _, _, another_var_needed, _ = line.split() as well as Prolog does offer, in order to exclude the famous singleton variables. I'm not sure, but wouldn't it avoid unnecessary allocation? Or creating references to the result of the split call does not count up as overhead? EDIT: Sorry, my point here is: in Prolog, as far as I'm concerned, in an expression like: test(L, N) :- test(L, 0, N). test([], N, N). test([_|T], M, N) :- V is M + 1, test(T, V, N). The variable represented by _ is not accessible, for what I suppose the reference to the value that does exist in the list [_|T] is not even created. But, in Python, if I use _, I can use the last value assigned to _, and also, I do suppose the assignment occurs for each of the variables _ -- which may be considered an overhead. My question here is if shouldn't there be (or if there is) a syntax to avoid such unnecessary attributions.

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  • Power function in prolog

    - by NHans
    Exactly what's the prolog definition for power function. I wrote this code and it give some errors I wanna know exact code for the power function. pow(X,0,1). pow(X,Y,Z):-Y1=Y-1,pow(X,Y1,Z1),Z1=Z*X. Anything wrong with this code?

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  • amzi prolog + eclipse question

    - by alan
    hey guys i have a question regarding amzi prolog with eclipse, Im running a .pro file which executes a breadth first search and if queue gets too long, the following error message appears: system_error 1021 Control stack full. Compile code or increase .cfg parameter 'control' If so, how may i run the compiled code under eclipse? I've tried running the project but the listener just ends without accepting any queries....?

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  • Prolog: Finding the Nth Element in a List

    - by Thomas
    I am attempting to locate the nth element of a List in Prolog. Here is the code I am attempting to use: Cells = [OK, _, _, _, _, _] . ... next_safe(_) :- facing(CurrentDirection), delta(CurrentDirection, Delta), in_cell(OldLoc), NewLoc is OldLoc + Delta, nth1(NewLoc, Cells, SafetyIdentifier), SafetyIdentifier = OK . Basically, I am trying to check to see if a given cell is "OK" to move into. Am I missing something?

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  • Where is Prolog used for traffic control systems?

    - by Masi
    The user Laurent had an interesting reply to the question [Why hasn’t logic programming caught on?]: If you look at the influence logic-programming has had in the field of -- air traffic control -- I don't think it can be said logic-programming has not caught on. A question arises: Where is prolog used for traffic control systems on the roads? Why is it used instead of languages, such as C or Python, in such environments?

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  • 'if' in prolog?

    - by jreid9001
    Probably a stupid question, but I can't find any documentation anywhere for it. Is there a way to do an if in prolog, e.g. if a variable is 0, then to do some actions (write text to the terminal). An else isn't even needed, but I can't find any implementation of if.

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  • prolog program to find equality of two lists in any order

    - by Happy Mittal
    I wanted to write a prolog program to find equality of two lists, the order of elements doesn't matter. So I wrote following: del( _ , [ ] , [ ] ) . del( X , [ X|T ] , T ). del( X , [ H|T ] , [ H|T1 ] ) :- X \= H , del( X , T , T1 ). member( X, [ X | _ ] ) . member( X, [ _ | T ] ) :- member( X, T ). equal( [ ], [ ] ). equal( [X], [X] ). equal( [H1|T], L2 ) :- member( H1, L2 ), del( H1, L2, L3), equal(T , L3 ). But when I give input like equal([1,2,3],X)., it doesn't show all possible values of X. instead the program hangs in the middle. What could be the reason?

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  • PROLOG all different

    - by inspectorG4dget
    Hello SO, I have a very weird problem with PROLOG. I have used it before, but it's been a while and I'm rusty. I have a list of variables and I need to ensure that none of them are the same. I have tried: use_module(library(bounds)). all_different(A, B, C, D, 6, 8). However, when I try this, I get an error saying that all_different/6 is undefined. How can I go about solving this issue? Is there any library function that I can call directly for this? I am VERY stuck and would greatly appreciate any help. Thanks in advance.

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  • Prolog newbie question: Making a procedure to print Hello World

    - by dmindreader
    I want to load this simple something into my Editor: Write:-repeat,write("hi"),nl,fail. So that it prints "hi". What should I do? I'm currently trying to do File->New and Saving a file named Write into E:\Program Files\pl\xpce\prolog\lib When doing the query: ?-Write. It's printing: 1 ?- Write. % ... 1,000,000 ............ 10,000,000 years later % % >> 42 << (last release gives the question) Why?

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  • Prolog n00b question: Doing whatever

    - by dmindreader
    I want to load this simple something into my Editor: Write:-repeat,write("hi"),nl,fail. So that it prints "hi". What should I do? I'm currently trying to do File->New and Saving a file named Write into E:\Program Files\pl\xpce\prolog\lib When doing the query: ?-Write. It's printing: 1 ?- Write. % ... 1,000,000 ............ 10,000,000 years later % % >> 42 << (last release gives the question) Why?

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  • Display radio buttons in prolog xpce

    - by Ben03
    I created a menu with Radio Buttons in XPCE prolog, but my radio buttons are showing on the same line, and I want to have each one on a separate line. My code is the following: new(D, dialog('title')), send(D, size, size(500,500)), send(D, append, new(Op, menu(options, marked))), send(Op, append, option1), send(Op, append, option2), send(Op, append, option3), send(Op, size, size(300,300)), send(D, display, Op, point(100, 40)), send(D, append(new(B1,button(ok, message(D, return, Op?selection))))), send(D, display, B1, point(100, 100)), send(D, append(button(cancel, message(D, return, @nil)))), send(D, default_button(ok)), get(D, confirm, Rval), free(D). Thanks in advance

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