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Ask HN: What's Prolog like in 2024?

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Re: Ask HN: What's Prolog like in 2024?

#151

Post by rramadass »

btbuildem wrote: post #139
rramadass wrote: post #50

Though i only know Prolog cursorily it is in my todo list of languages to study. I think it has great value in that it teaches you a different paradigm for programming. You might also want to look at Erlang which is used in the Industry and would be helpful for your future. Joe Armstrong was originally inspired by Prolog and he conceived Erlang as Prolog-Ideas+Functional/Procedural+Concurrency+Fault-Tolerance. Hence…

Ha! That explains a lot. I've started looking into Prolog recently, and there were some... familiar echoes in there, reminiscent of Erlang. But of course, the submarine is like a cigar, not cigar like a submarine.

The Development of Erlang by Joe Armstrong (pdf) - https://dl.acm.org/doi/pdf/10.1145/258948.258967

Re: Ask HN: What's Prolog like in 2024?

#152

Post by xyproto »

7thaccount wrote: post #124
epgui wrote: post #123

Earlier quoted context omitted.

Clojure is probably the most beautiful language I've ever worked with. Nothing is perfect, but Clojure is very simple and elegant.

Only downside is I don't know Java, so some things that should be obvious are opaque to me.

Java frolicks in opaqueness.

Re: Ask HN: What's Prolog like in 2024?

#153

Post by triska »

b800h wrote: post #103
jodrellblank wrote: post #28

Earlier quoted context omitted.

There are some benchmarks here of SWI Prolog's benchmark suite on diffrent Prolog systems by Jan Wielemaker the SWI Prolog author: https://swi-prolog.discourse.group/t/porting-the-swi-prolog-... He finds Scryer performs worse, which he does comment on, he also explains some tradeoffs and historic choices in SWI's design which affects its performance. I think I have seen the author of Scryer saying that's not surprisi…

So SWI appears to be more performant, it has an open license, so as per the GGP's claim regarding Scryer in the post above, it must not be ISO-compliant?

A key performance attraction of Scryer Prolog is its space efficiency for representing lists of characters, yielding a 24 times (!) more compact representation than a naive implementation would.

With Scryer Prolog and other recent systems that implement this representation, such as Trealla Prolog, we can easily process many GBs of text with DCGs, arguably realizing the full potential of the originally intended use case of Prolog for the first time. Trealla Prolog goes even further already, and allows overhead-free processing of files, using the system-call mmap(2) to virtually map files to memory, delegating the mapping to the operating system instead of the Prolog system.

The linked benchmarks do not test these aspects at all, and in addition use a version of Scryer Prolog that was completely outdated already at the time the benchmarks were made: The benchmarks use Scryer Prolog v0.8.127, which was tagged in August 2020, more than 3 years (!) before the benchmarks were posted. The linked benchmarks thus ignore more than 3 years of development of a system that was at that time 7 years old. Newer versions of Scryer Prolog perform much better due to many improvements that have since been applied. More than 1700 commits were applied between these dates.

In the face of the 24-fold reduction of memory use that the above-mentioned efficient string representation enables, small factors of difference in speed between different systems are in my opinion barely worth mentioning at all in any direction.

And yes, in addition to this great space efficiency, the strong ISO conformance of Scryer Prolog is also a major attraction especially when using it in highly regulated areas. For example, here is a recently envisaged application of Scryer Prolog in the context of machine protection systems (MPS) of giant particle accelerators, where adherence to industry standards is of great importance for warranty reasons among others:

https://github.com/mthom/scryer-prolog/discussions/2441

As another example, a medical application of Scryer Prolog, in the highly regulated domain of oncology trial design:

https://github.com/mthom/scryer-prolog/discussions/2332

Here is an overview of syntactic ISO conformance of different Prolog systems:

https://www.complang.tuwien.ac.at/ulrich/iso-prolog/conformi...

Re: Ask HN: What's Prolog like in 2024?

#154

Post by rramadass »

tannhaeuser wrote: post #145
rramadass wrote: post #50

Though i only know Prolog cursorily it is in my todo list of languages to study. I think it has great value in that it teaches you a different paradigm for programming. You might also want to look at Erlang which is used in the Industry and would be helpful for your future. Joe Armstrong was originally inspired by Prolog and he conceived Erlang as Prolog-Ideas+Functional/Procedural+Concurrency+Fault-Tolerance. Hence…

Sure, Erlang was prototyped on Prolog because Prolog has excellent built-in facilities for domain-specific languages: you can define new unary or binary operators along with priorities and associativity rules (you can use this to implement JSON or other expression parsing in like two lines of code, which is kindof shocking for newcomers, but comes very handy for integrating Prolog "microservices" into backend stacks)…

In The Development of Erlang Joe Armstrong says "We concluded that we would like something like Prolog with added facilities for concurrency and improved error handling".

See pdf linked here - https://news.ycombinator.com/item?id=40998632

Re: Ask HN: What's Prolog like in 2024?

#155

Post by z5h »

In theory, Prolog is the king of languages. Simultaneously a logical formalism, and (with a resolution system) a language for computation, AND the ultimate meta-programming language as its homoiconic but only goals are evaluated (there is no eager/lazy evaluation fuss - a term is just a term), and goals can only succeed (and have any consequence) if there is already a matching clause.

In practice, there are some very performant and maintained implementations with small but helpful communities.

Also in practice. With all of this power, it's clear that anything could be done (well) in Prolog, but it's not always clear what that way might be. DCGs are an example of a beautiful, elegant, simple, powerful way of building parsers (or state machines) that was not immediately evident to the Prolog community for some time. The perpetual conundrum as a user will be "I could do it this way, but there are certainly better ways of doing this, and I have many avenues I could explore, and I don't know which might be fruitful in what timeline".

Re: Ask HN: What's Prolog like in 2024?

#156

Post by strangattractor »

everforward wrote: post #136
jodrellblank wrote: post #116

What is it like? 50 years of historic cruft. Questionable whether there are more trip hazards than usefulness for ordinary coding. A fractured community which feels like there are more Prolog systems than Prolog code. Learning Prolog is less "how do I do things in Prolog" and more "how do I contort my things to avoid tripping over Prolog?". A few dedicated clever people and idealists and dreamers talking about ontolo…

> A few dedicated clever people and idealists and dreamers talking about ontologies and building things I don't understand I was briefly deeply interested in ontologies via OWL and I suspect Prolog has the same issues that I think plague ontologies in general. They are a fantastic tool for a system complex enough to be nearly useless. Modelling an ontology for a reasonably complex domain is unreasonably difficult. No…

I had similar discussions with people that wanted to encode published research into ontologies. I would ask researchers what they think - the answer was always great idea. I would then follow up with - How would you use it? No response. I finally concluded that it would never happen.

1. No one wanted it enough to pay for it to happen.

2. There is always a turn over of ideas coming and going which can never be sufficiently updated to keep it useful. Again no one would pay anyway.

Tools like LLMs seem to be fill the role now. I would like to see a Prolog integrated with LLMs is someway (lack of imagination fails me how that would happen).

Re: Ask HN: What's Prolog like in 2024?

#157

Post by jolt42 »

slashdave wrote: post #130
jodrellblank wrote: post #116

What is it like? 50 years of historic cruft. Questionable whether there are more trip hazards than usefulness for ordinary coding. A fractured community which feels like there are more Prolog systems than Prolog code. Learning Prolog is less "how do I do things in Prolog" and more "how do I contort my things to avoid tripping over Prolog?". A few dedicated clever people and idealists and dreamers talking about ontolo…

Who still has nightmares of infinitely nested parenthesis?

They seem to disappear with parinfer.

Re: Ask HN: What's Prolog like in 2024?

#158

Post by jolt42 »

chamomeal wrote: post #122
jodrellblank wrote: post #116

What is it like? 50 years of historic cruft. Questionable whether there are more trip hazards than usefulness for ordinary coding. A fractured community which feels like there are more Prolog systems than Prolog code. Learning Prolog is less "how do I do things in Prolog" and more "how do I contort my things to avoid tripping over Prolog?". A few dedicated clever people and idealists and dreamers talking about ontolo…

What do you mean by LISP as a siren call? I’ve just started learning clojure and besides the lack of static types (which is pretty harsh for me), it seems like a fun and practical language.

Lisps don't get in your way, but they also have no opinions, which is problematic for community development. As a static type fan, it's the only language I think the pros outweigh than one con.

Re: Ask HN: What's Prolog like in 2024?

#159

Post by Arch-TK »

kibwen wrote: post #84
gorkempacaci wrote: post #52

Prolog, and Constraint Programming especially are great to have in your toolbox. I’ve done research in the field for years, and my job in the industry today is writing Prolog. There are real issues with Prolog: - no proper module nor package system in the modern sense. - in large code bases extra-logical constructs (like cuts) are unavoidable and turn Prolog code into an untenable mess. SWI prolog has single-sided un…

> when you get how the types in every OO program is a Prolog program itself "Any sufficiently complicated type system contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Prolog."

Any sufficiently complex type system is indistinguishable from an esolang.

Re: Ask HN: What's Prolog like in 2024?

#160

Post by wkyleg »

I like Peter Norvig's book "Paradigms of AI Programming," where you learn old fashioned symbolic AI with LISP and Prolog. Is it outdated? Absolutely, but it is a classic read.

Maybe a use case for new AI models could be creating more old fashioned expert systems written in LISP or Prolog that are easier for humans to audit. Everything tends to come back full circle.

https://www.amazon.com/Paradigms-Artificial-Intelligence-Pro...

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