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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?

#251

Post by fulafel »

7thaccount wrote: post #176
epgui wrote: post #175

Earlier quoted context omitted.

You really don’t need to know any java. I don’t know java either. Even if you’re doing java interop, it’s quite easy to figure it out.

Last time I looked about file IO it involves calling out to some Java class that I had no clue about as I don't use Java. All the doc of the time just assumed you should be able to figure this all out. Edit: it's been like 5 years

The docs are better now (eg https://clojure-doc.org/articles/cookbooks/files_and_directo... ) but you still need to follow a Javadoc link every now and then for the full story.

Alternatively you can use a library such as https://github.com/babashka/fs .

I agree with the GP that you don't need to know any Java.

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

#252

Post by Karrot_Kream »

throwaway3306a wrote: post #216
Karrot_Kream wrote: post #181

Earlier quoted context omitted.

At this point, why not use one of the many other CP solver packages out there and the layers on top like OR-tools?

Which one is as developed, as universal and as capable as Prolog with CLP and/or DCG? Serious question, I'd like to have something that's easy to integrate with Node.js.

OR-Tools has a lot of bindings in different languages, though Javascript/Node doesn't seem to be a first-class supported environment. Looks like https://www.npmjs.com/package/node_or_tools ports a few solver packages into Node so if those solvers fit your needs you can use this package.

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

#253

Post by YeGoblynQueenne »

rramadass wrote: post #154
tannhaeuser wrote: post #145

Earlier quoted context omitted.

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

Yeah but to be honest, Erlang ended up being not something like Prolog at all.

I think Joe Armstrong was a user here and I interacted with him waaaay way back when I first joined. He's dead now :(

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

#254

Post by YeGoblynQueenne »

Here's what I'm doing with Prolog:

https://github.com/stassa/louise

Louise is a Meta-Interpretive Learning (MIL) system. MIL is like a second-order Prolog where first-order programs are learned from higher-order programs by Resolution. There's a long thread of literature on MIL going back to 2014 but it now seems we're starting to move towards applications, e.g. I'm doing a post-doc where I use MIL to learn autonomous behaviours for an agent that must guide a mobile robot in survey missions. Other colleagues are working on applications in biology. We're going slowly because there's very few of us but MIL is a powerful technique that extends the soundness and completeness of SLD-Resolution to induction, so I'm hopeful that good things will happen with a bit of elbow grease and a bit of patience.

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

#255

Post by shrimp_emoji »

tashmahalic wrote: post #166
shrimp_emoji wrote: post #41

Earlier quoted context omitted.

It was a whirlwind "survey of languages" course. After blowing our minds with functional programming via OCaml, the last segment was traditionally logical programming via Prolog. But he decided to spare us, I guess, and made me fall in love with Rust for a few years. :p (Or he sadistically meant to inflict the trauma of knowing how much better C and C++ could be but never will be, which stays with you even after you…

I’d love to hear more about your trauma :-). What are the main ways C and C++ could be better?

The easiest answer: they should have a build and test and packaging system like Cargo built-in. The best you have is a tedious anarchy of third-party systems, of which CMake seems to have come out the winner. I use CMake, but it's no Cargo (as an understatement).

Borrowing and ownership is great for building safe code, whether it's single- or multi-threaded. In C, you have a nest of pointers, and a pointer communicates nothing about the ownership of its memory. Stuff can go, and leak, and dangle, everywhere. C++ mitigated this a little with references. Then it bolted on smart pointers, mitigating it further. Without learning Rust, though, I don't think I'd be as good of a C/C++ programmer because, unlike Rust, those languages don't force you to think about where memory lives and where it's going.

The module system is also way better.

Then I could take cheap shots: `u8` is way better than `uint8_t`. Rust had slices from the beginning, to be able to refer to parts of strings in a cheap way with easy syntax, whereas only C++17 introduced the comparatively awkward `std::string_view`.

There are ways I think Rust is worse though! The easiest is that it still doesn't have a standard and will probably not see the uniquely deep and broad support of C/C++ in my lifetime. :p

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

#256

Post by epgui »

xigoi wrote: post #229
harperlee wrote: post #227

Earlier quoted context omitted.

Could you expand why? It's not immediately obvious why would that be, my understanding is that the general consensus around here is that the JVM is a superb piece of tech with a bad rap due to java the language.

Slow startup, huge memory consumption, design that inherently favors class-based languages like Java, the frequent need to use Java libraries.

> Slow startup

This makes the jvm a bit less suitable for programmes with short lifetimes (like lambdas), depending on how sensitive startup times are in context... But is mostly irrelevant in long-lived applications like services.

> design that inherently favors class-based languages like Java

Clojure abstracts over this so well that it's really a non-issue for a wide array of use cases / applications. When programming in Clojure, you really don't have to think about objects and classes at all, unless you really insist on doing so.

> frequent need to use Java libraries

This would be going against the grain: you will have a much better time by staying within native Clojure. I've worked on commercial/production applications that barely had any java interop, and whatever java interop there was was rarely ever involved in day to day work.

---

Disclaimer: I also am not a huge fan of the JVM and I really dislike the Java world generally, but it never stood in the way of me getting stuff done with Clojure.

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

#257

Post by drdeca »

HelloNurse wrote: post #233
drdeca wrote: post #171

Earlier quoted context omitted.

I don’t see an issue with saying “X-ray photography machines, and deep-space radio telescopes, are (or at least contains-a, in the case of the telescope) cameras”. They just aren’t ordinary cameras of the sort that a typical person might take a picture with. I think most of the reasoning you would want to do with a concept of “camera” that excludes X-ray machines and telescopes, but includes night-vision, could be ha…

An universal ontology cannot have any notion of an "ordinary" camera, not because of expressive limitations but because it's subjective. Is a CAT machine a camera? Maybe only its sensor and the computers that reconstruct images? Maybe just the sensor? It mostly depends on your location in the supply chain. Is a box with a projection plane and no means to capture images a camera? Before about 1830, definitely (and the…

I don’t think the “before 1830” case is really an issue. That’s just an example of the meaning of words changing.

I didn’t mean that “ordinary camera” should be a term in the formal ontology. I meant something more like “If you want to formalize the notion of ‘a camera’, it should include the CAT machine and telescope. If you want to address only the types of cameras that you think of as ordinary cameras, you should add extra qualifiers to get at what you mean.” .

(Where, “what you mean” might not get the term “ordinary camera”, but something more clear and descriptive.)

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

#258

Post by wwweston »

jimbokun wrote: post #129
tannhaeuser wrote: post #105

Earlier quoted context omitted.

I'd advise to not use Prolog as general-purpose programming language, but as an embedded DSL or as a service for the part it's really suited for (if your app involves exploration and search over a large combinatorical space in the first place, such as in discrete optimization in industry, logistics, and finance). You really don't need yet another package manager and pointless premature modularization for modelling yo…

To me this makes Prolog sound like a tool to reach for similar to SQL. Specialized language for asking specific kinds of search or query over your data.

I've also wondered why Prolog or at least Datalog isn't available/used more widely as a query layer, especially considering that the promise of SQLs natural-ish language really didn't lead to a level of adoption among non-tech workers even approaching the popularity of the spreadsheet, so the reason for that style of syntax didn't really pan out, and Prolog would appear to have some syntactic and capability advantages.

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

#260

Post by ArtixFox »

shrimp_emoji wrote: post #255
tashmahalic wrote: post #166

Earlier quoted context omitted.

I’d love to hear more about your trauma :-). What are the main ways C and C++ could be better?

The easiest answer: they should have a build and test and packaging system like Cargo built-in. The best you have is a tedious anarchy of third-party systems, of which CMake seems to have come out the winner. I use CMake, but it's no Cargo (as an understatement). Borrowing and ownership is great for building safe code, whether it's single- or multi-threaded. In C, you have a nest of pointers, and a pointer communicat…

There are more criticisms of rust and c++ but sure.
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