11–20 of 20 posts
If you need a rules engine, great, but there's no reason to shoe-horn general programming problems into the Prolog model.
If you have JESS / Java or CLIPS / C, or generally, a rules engine for your favourite language, what does Prolog bring to the table?
Prolog has its limitations, but it still stands out as one of the oldest, influential and important declarative programming languages. IMHO, it's hard to say what is the natural successor to Prolog. For all that it shares with Lisp, it definitely has never shared even a fraction of the popularity. They have two entirely different approaches and purposes though, so this isn't terribly surprising. Even if someone does…
{ active(A) } :- thing(A).
You an also write pure constraints, like:
:- active(duck), active(cat).
The main downside in my experience is that ASP doesn't do well on large programs, even large-but-simple ones that Prolog handles well, due to the fact that ASP is grounding everything to the moral equivalent of giant SAT problems. Particularly if you use numerical reasoning over non-tiny ranges. Say, you have some sprites on a grid, and at each time, each sprite has exactly one X/Y position:
canvas_x(0..799).
canvas_y(0..599).
timestep(0..99).
sprite(mario;luigi;babomb).
1 { pos(S,X,Y,T) : sprite(S) : canvas_x(X) : canvas_y(Y) } 1 :- timestep(T).
Prolog has its limitations, but it still stands out as one of the oldest, influential and important declarative programming languages. IMHO, it's hard to say what is the natural successor to Prolog. For all that it shares with Lisp, it definitely has never shared even a fraction of the popularity. They have two entirely different approaches and purposes though, so this isn't terribly surprising. Even if someone does…
Here's a link: http://www.cs.sunysb.edu/~warren/xsbbook/book.html
While not familiar with Prolog, I understand that Erlang's pattern matching comes from that world - so Erlang? EDIT: Here's a couple references for the Erlang/Prolog connection... http://www.erlang.org/faq/academic.html http://hyperpolyglot.org/logic Also I found this while looking for the reference for the Prolog/Erlang connection... http://www.slideshare.net/adorepump/learning-erlang-from-a-p...
Prolog has its limitations, but it still stands out as one of the oldest, influential and important declarative programming languages. IMHO, it's hard to say what is the natural successor to Prolog. For all that it shares with Lisp, it definitely has never shared even a fraction of the popularity. They have two entirely different approaches and purposes though, so this isn't terribly surprising. Even if someone does…
I've also switched to ASP, largely because of choice rules plus filtering. You can write things like: { active(A) } :- thing(A). Which says that for all things A, active(A) is a free choice of true or false, constrained by the requirement to be consistent with all other clauses in the program. That lets you do abductive reasoning, e.g. find an explanation, plan, or cause from a possibility space, consistent with the…
While not familiar with Prolog, I understand that Erlang's pattern matching comes from that world - so Erlang? EDIT: Here's a couple references for the Erlang/Prolog connection... http://www.erlang.org/faq/academic.html http://hyperpolyglot.org/logic Also I found this while looking for the reference for the Prolog/Erlang connection... http://www.slideshare.net/adorepump/learning-erlang-from-a-p...
Prolog's unification is quite a bit more powerful than Erlang's pattern matching, though. You can't pass around uninstantiated variables in Erlang. Erlang also discarded backtracking (because it mixes poorly with concurrency).
Earlier quoted context omitted.
I've also switched to ASP, largely because of choice rules plus filtering. You can write things like: { active(A) } :- thing(A). Which says that for all things A, active(A) is a free choice of true or false, constrained by the requirement to be consistent with all other clauses in the program. That lets you do abductive reasoning, e.g. find an explanation, plan, or cause from a possibility space, consistent with the…
The wikipedia page didn't really shed much light on what ASP is doing under the hood. How does it differ from constraint solvers like http://www.gecode.org/ ? I know that gecode can handle problems like your canvas example well by representing integer variables as sets of intervals. What kind of problems would ASP have the advantage on?
I think of ASP as "a semantically nicer Prolog, plus extensions". It originated as one of the attempts to give Prolog's semantics, which are logic-inspired but defined by its procedural goal-chaining algorithm, a clean declarative logical semantics. The "stable model semantics" were one of the competing ones, which became answer-set programming.
It depends on which constraint solver exactly, but two features not present in most pure constraint-solving systems are the Prolog-style deductive reasoning, and negation-as-failure. ASP lets you freely intermingle deductive reasoning chains with constraints, rather than solving things as purely sets of variables with constraints on them (though this is true of other approaches that fall under the "constraint logic programming" heading as well). That lets you do the generate-and-filter style, where you might have a complex deductive logic program generating possibilities, and then effectively a constraint program filtering from them (and the constraint part can sometimes call out to deductive reasoning chains as well, since it's all the same language).
ASP semantics are sort of a superset of Prolog + constraint solvers + abductive reasoners, where you can freely intermingle all those approaches. As a result it isn't, yet anyway, the most efficient reasoner if you fall more squarely into one of those paradigms. Here's an experimental ASP system that also adds efficient constraint variables, though: http://www.cs.uni-potsdam.de/clingcon/
Prolog has its limitations, but it still stands out as one of the oldest, influential and important declarative programming languages. IMHO, it's hard to say what is the natural successor to Prolog. For all that it shares with Lisp, it definitely has never shared even a fraction of the popularity. They have two entirely different approaches and purposes though, so this isn't terribly surprising. Even if someone does…
10 or 11 years ago, David Warren was working on an extension called Tabled Logic Programming; his implementation was called XSB. He seems to have abandoned it, which I find disappointing; it looked interesting. In a nutshell, instead of a goal acting like a procedure call as in Prolog, it acts like a coroutine. Here's a link: http://www.cs.sunysb.edu/~warren/xsbbook/book.html