westurner 3 months ago

Cool tests! PyDatalog does Datalog (which is ~Prolog, but similar and very capable) logic programming with SQLAlchemy (and database indexes) and apparently NoSQL support. https://sites.google.com/site/pydatalog/

Datalog: https://en.wikipedia.org/wiki/Datalog

... TBH, IDK about logic programming and bad facts. Resilience to incorrect and incredible information is - I suppose - a desirable feature of any learning system that reevaluates its learnings as additional and contradictory information makes its way into the datastores.

  • photon_lines 3 months ago

    Thanks for the feedback :) I'll definitely check out Datalog - I didn't realize they had logic programming integrated with SQLAlchemy, so it definitely sounds interesting!

tluyben2 3 months ago

Nicely done! I have been trying to implement actual usable (as in, they can be used as a scripting language for instance to build anything) languages in as few lines as I can (without making them unreadable). Ofcourse that's more as a challenge than anything serious, but it is fun. A minimal implementation I define as being something that can parse the language, interpret it and has FFI to add whatever else you may need. So far I got down to around 50 lines in C# [0].

0. https://gist.github.com/tluyben/16ee2645c4c8aed813005d51488d...

etaioinshrdlu 3 months ago

This is about 10x larger than i would call a few lines :)

  • MrOxiMoron 3 months ago

    still way less lines then I would have thought, especially because it has no dependencies.

    • bhargav 3 months ago

      But the title does not mention that. It says few lines. Maybe 100, 200, 300 lines are few. Its misleading and otherwise discredits a good project.

      This project even has a GUI/IDE. I believe that is a stronger selling point rather than "few" lines of code or "little work", "easy way" or any of these other colloquial 'flexing' terms.

      • ghusbands 3 months ago

        It's worse than that - the title says "a few", which is basically always less than ten. If it said "quite a few", it would certainly be accurate. If it actually said "few", it wouldn't be as bad, though still misleading.

sanxiyn 3 months ago

FYI, there is a mature implementation of this idea called YieldProlog.

  • photon_lines 3 months ago

    Thanks :) Yup, there are also constraint programming libraries in Python which can be used for providing similar functionality, and they're definitely worth checking out!

garganzol 3 months ago

Very impressive.

Does anybody use Prolog scripting engine as part of their applications? For example, to write a solution lookup function for some specific problem that would be a nightmare to solve otherwise.

As a side note, I found that Lisp (the Scheme flavor) is essential in many applications. First of all, as a small and capable templating engine. Secondly, as a sophisticated NLP (natural language processing) engine.

  • tannhaeuser 3 months ago

    I've used ad-hoc test case generation using Prolog (MC/DC, all-permutations and other combinatorials) which is a quite natural application for Prolog. Around 2005 I've also used Prolog to generate Java code for analysing/monitoring business processes based on formal business process descriptions on a research project for a Telco who went all-in on SOA. As part of that, I also started to develop decision procedures for static type checking of XML-manipulating programs, along with validators for common markup meta-languages (XSD and subsets). Many years ago I've also developed custom file parsing/business rules checking using Prolog. Plus, a couple ad-hoc parsers and DSLs. And, having developed 2 1/2 prolog engines so far, I'm planning to include ISO Prolog in my upcoming document storage/search system based on SGML, where Prolog is an excellent match since it's both an ISO standard (like SGML), and even has a binding to a document query language based on ISO/IEC 13250 (eg. the proposed "tolog" language, though alternatives were proposed and an ISO/IEC 13250 query language was never completed as a standard).

  • jifu 3 months ago

    I wrote a simple date extractor (parsing stuff like "two days ago" from strings) for my hobby website project in prolog [0]. It was great fun to write, and prolog really shines in such applications. And running a prolog microservice in docker feels just a little perverse in a good way. :)

    [0] https://github.com/jvnn/date-extractor

timClicks 3 months ago

How long did it take you to grok unification? It has always seemed quite mindbending to me and I don't think that I have ever properly understood what's happening

  • photon_lines 3 months ago

    I didn't grok anything at first actually. I had familiarity with Prolog and wanted a refresher, so I decided to take a look at implementation attempts done in other languages. I found one which did it in a few lines of Javascript, and you can find the full read and implementation here: https://curiosity-driven.org/prolog-interpreter . My apologies if I didn't make it clear that this is a port of the original write up - I did include this in the first paragraph of the README though, so maybe I should have been clearer?

    Originally, I was trying to learn Kotlin along with wanting a refresher in Prolog, so I attempted to do the port using Kotlin and gave up half way though. I didn't have the patience to try to grok too many things at once, so I decided to go with Python due to it's simplicity, popularity, as well as the fact that I'm a lot more fluent in it than I am in Kotlin.

    Anyways - sorry if I'm going off track. To answer your question, I grokked the implementation details through porting / refactoring the original code. The concepts / unification I was already familiar with from taking a university course which involved Prolog and from using it in a large AI project. From what I remember, it took me quite a long time to grasp the language and its power!!

truth_seeker 3 months ago

Nice. For complex operations with reasonably sized data pypy would be a good choice.

inetsee 3 months ago

Racket also has a Prolog-Style Logic Programming DSL named Racklog.