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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?

#201

Post by koito17 »

ghufran_syed wrote: post #193
koito17 wrote: post #185

Earlier quoted context omitted.

Yup. I learned Clojure just so I can use a Lisp and get paid for it, but there is some weird cult against all forms of typing. Even coming from a Common Lisp background, this was strange to me. In Common Lisp, there are implementations (like SBCL and ECL) that can make use of type declarations to produce efficient machine code and allow the compiler to catch errors that would otherwise be run-time errors. There's als…

Could you use https://github.com/clojure/core.typed ? Or https://clojure.org/guides/spec ?

Typed Clojure is interesting. However, until two months ago, it was practically unusable for most Clojure projects because of the lack of type inference in higher-order functions. This has changed, but there's another huge problem: nobody maintains type declarations for widely used libraries. If you look at alternatives to TypeScript, such as ReScript, you will find similar issues.

I still use Clojure, but I am fully aware of the kind of bugs to expect down the road. Typed Clojure would work if I could maintain types for each library I use, but that is simply too much effort on my part.

As for clojure.spec, I already addressed this in my post, but I will state the following.

Schema, Malli, and Spec are not substitutes for a type system. Each of these libraries explicitly state so. You still need to enable instrumentation and run erroneous code violating some contract. Most Clojure programmers have the habit of enabling instrumentation in dev and disabling it in production because validation is an expensive operation. I personally use Malli for data validation and coercion, but it does not make refactoring any easier, nor does it help autocomplete and other development-related tooling.

(Someone will probably link a malli document demonstrating clj-kondo linter generation, but even that is not a substitute. At best it detects arity errors and primitive type mismatches, not the shape of data in a map).

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

#202

Post by zdragnar »

worik wrote: post #197
everforward wrote: post #136

Earlier quoted context omitted.

> 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…

Ontology: Study of the nature of being, becoming, existence or reality, as well as the basic categories of being and their relations (philosophy) What does that have to do with this? Is there some use of "ontology" in logic I have not heard of?

Domain Driven Design - one of those things like Agile that triggers all sorts of holy wars - has a lot of overlap with the general concept of ontologies, to the point that I've seen some teams formalize all communication between microservices through a shared "ontology", which in reality was essentially a giant XML based descript of valid nouns and verbs that events could use to communicate between services.

Additionally, there's a good deal of overlap with the "semantic web" concept, which itself had a good deal of hype with very limited (but important) application- even the W3C has some published content on how all three fit together: https://www.w3.org/2001/sw/BestPractices/SE/ODA/

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

#203

Post by everforward »

worik wrote: post #197
everforward wrote: post #136

Earlier quoted context omitted.

> 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…

Ontology: Study of the nature of being, becoming, existence or reality, as well as the basic categories of being and their relations (philosophy) What does that have to do with this? Is there some use of "ontology" in logic I have not heard of?

It would be this version of ontology: https://en.wikipedia.org/wiki/Ontology_(information_science)

Loosely speaking, ontologies are categories of objects defined by their attributes and relationships to other things. Where a hierarchy is a branching structure where items can only appear on the tree once, ontologies do not require everything to stem from a single "root" node and items can appear in the tree in more than one place.

It's a way of working around how hierarchies can't model some things very well. E.g. "bipedal" is an attribute that can apply to both animals and robots; where does it go in a hierarchy that it can apply to both animals and robots without also implying that robots are animals or vice versa.

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

#204

Post by kazinator »

derdi wrote: post #165
ted_dunning wrote: post #131

Earlier quoted context omitted.

To be precise, a small number of very small Prolog programs can be run backwards. There are essentially no significant Prolog programs that are reversible with acceptable efficiency.

To be even more precise, Prolog programs only ever run forward because the order of evaluation is fixed as top-down, left-to-right. These notions of "forward" and "backward" are very unhelpful and should be given up. Beginners find the order of evaluation hard enough to understand, let's not confuse them even more. Also, the notion is woefully incomplete. Let's say we consider this "forward": ?- list_length([a, b, c]…

What's going on in the second example? Did Prolog generate a list term stuffed with gensym variables, which satisifies the list_length being 3?

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

#205

Post by [deleted] »

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…

[deleted]

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

#206

Post by asimpletune »

wk_end wrote: post #150
chamomeal wrote: post #122

Earlier quoted context omitted.

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.

Imagine it's, like, 1980 - or even earlier - and you can work in a language roughly as nice as Clojure, except the rest of the world is stuck working with pre-ANSI C or Pascal or FORTRAN or COBOL or raw assembly language. There's no Python or Java or C# or Ruby or Perl or Haskell or Scala or Kotlin or Rust or JS/TS. Nothing really resembling our modern idea of a high-level language. (OK, there was Smalltalk. Let's ig…

Learning about the curse of lisp is always an eye opening point in one’s career

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

#209

Post by andrewflnr »

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

This was my experience too, at about the same time. I should really dig back into it at some point.

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

#210

Post by triska »

derdi wrote: post #179
triska wrote: post #174

Earlier quoted context omitted.

> the links you provided describe these applications without references to warranties and standards and regulation. This is not true. For example, quoting from page 2 of the paper that is linked to in a discussion I posted, An Executable Specification of Oncology Dose-Escalation Protocols with Prolog , available from https://arxiv.org/abs/2402.08334 : "Standards are of great importance in the medical sector and play…

I acknowledge that you also included your nice talking point in a paper you published on arXiv. Citing yourself doesn't convince me any more of the credibility of this argument. > is there even the slightest doubt about the importance of standards when building and operating giant particle accelerators The particle accelerator application is a checker for existing JSON config files. The accelerator is already running…

> CLP(Z), which does not have an ISO standard

CLP(FD/Z) is a candidate for inclusion in the Prolog standard: Several Prolog systems provide it with notable commonalities in features, it fits perfectly into the existing language, and it follows the logic of the standard including its error system. It can even be implemented within Prolog, provided a few basic features are present in a Prolog system. For instance, the CLP(Z) system I provide and which is used in the paper runs with little modifications already in several different Prolog systems, including SICStus, Scryer and Trealla. CLP(FD/Z) is an admissible extension of the existing standard:

    5.5 Extensions

    A processor may support, as an implementation specific
    feature, any construct that is implicitly or explicitly
    undefined in the part of ISO/IEC 13211.
This is completely different from modifications of the standard that do not fit at all into the standard. For instance, interpreting double-quoted strings differently from what the standard prescribes is not an extension in the sense the standard defines it, but a modification of the standard.

In addition, Scryer Prolog has an execution mode where all its extensions are turned off. This is called a strictly conforming mode, and is also prescribed by the standard:

    5 Compliance

    5.1 Prolog processor

    A conforming Prolog processor shall:

      ...

      e) Offer a strictly conforming mode which shall reject
      the use of an implementation specific feature in Prolog
      text or while executing a goal.
In Scryer Prolog, the strictly conforming mode is the default execution mode.

Regarding the other points you mention: Even though it may sound easy to say "as long as that dialect has a reliable specification and implementation", I know no such system that exists, and what I see from systems that do not adhere to the Prolog standard makes me doubt that such a thing is possible. The systems that do not follow the standard often have elementary syntactic problems, such as reading a Prolog term that they themselves emit into a different Prolog term, a recipe for disaster and unacceptable in every domain I know.

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