Learn Prolog Now (2006) • Hacker News Board

Re: Learn Prolog Now (2006)

#31

Post by ecshafer » Wed, Nov 12, 2025, 5:08 PM UTC

WillAdams wrote: post #14

qsort wrote: post #7

Earlier quoted context omitted.

Python wins out in the versatility conversation because of its ecosystem, I'm still kinda convinced that the language itself is mid. Prolog has many implementations and you don't have the same wealth of libraries, but yes, it's Turing complete and not of the "Turing tarpit" variety, you could reasonably write entire applications in SWI-Prolog.

Right, Python is usually the second-best choice for a language for any problem --- arguably the one thing it is best at is learning to program (in Python) --- it wins based on ease-of-learning/familiarity/widespread usage/library availability.

I don't know if I would say its second-best. It just happened to get really popular because it has relatively easy syntax, and Numpy is a really great library making all of those scientific packages that people were using Fortran and C++ for before available in an easier language. This boosted the language, right when data science became a thing, right when dynamic programming became popular, right when there was a boost in Learn 2 Code forget about learning fundamentals was a thing. Its an okay language I guess, but I really think it was lucky that Numpy exists and Numby or Numphp.

Re: Learn Prolog Now (2006)

#32

Post by quux » Wed, Nov 12, 2025, 5:10 PM UTC

yes

Re: Learn Prolog Now (2006)

#33

Post by lmf4lol » Wed, Nov 12, 2025, 5:10 PM UTC

ux266478 wrote: post #17

Prolog really is such a fantastic system, if I can justify its usage then I won't hesitate to do so. Most of the time I'll call a language that I find to be powerful a "power tool", but that doesn't apply here. Prolog is beyond a power tool. A one-off bit of experimental tech built by the greatest minds of a forgotten generation. You'd it find deep in irradiated ruins of a dead city, buried far underground in a bunke…

When I entered university for my Bachelors, I was 28 years old and already worked for 5 or 6 years as a self-taught programmer in the industry. In the first semester, we had a Logic Programming class and it was solely taught in Prolog. At first, I was mega overwhelmed. It was so different than anything I did before and I had to unlearn a lot of things that I was used to in "regular" programming. At the end of the class, I was a convert! It also opened up my mind to functional programming and mathematical/logical thinking in general.

I still think that Prolog should be mandatory for every programmer. It opens up the mind in such a logical way... Love it.

Unfortunately, I never found an opportunity in my 11 years since then to use it in my professional practice. Or maybe I just missed the opportunities?????

Re: Learn Prolog Now (2006)

#34

Post by samuell » Wed, Nov 12, 2025, 5:11 PM UTC

I love Prolog, and have seen so many interesting use cases for it.

In the end though, it mostly just feels enough of a separate universe to any other language or ecosystem I'm using for projects that there's a clear threshold for bringing it in.

If there was a really strong prolog implementation with a great community and ecosystem around, in say Python or Go, that would be killer. I know there are some implementations, but the ones I've looked into seem to be either not very full-blown in their Prolog support, or have close to non-existent usage.

Re: Learn Prolog Now (2006)

#35

Post by rootnod3 » Wed, Nov 12, 2025, 5:12 PM UTC

ecshafer wrote: post #29

I really enjoyed learning Prolog in university, but it is a weird language. I think that 98% of tasks I would not want to use Prolog for, but for that remaining 2% of tasks it's extremely well suited for. I have always wished that I could easily call Prolog easily from other languages when it suited the use case, however good luck getting most companies to allow writing some code in Prolog.

That is where Lisp or Scheme weirdly shines. It is incredibly easy to add prolog to a Lisp or a Scheme. It’s almost as if it comes out naturally if you just go down the rabbit hole.

“The little prover” is a fantastic book for that. The whole series is.

Re: Learn Prolog Now (2006)

#36

Post by svieira » Wed, Nov 12, 2025, 5:13 PM UTC

ramses0 wrote: post #15

zemptime wrote: post #10

I've recently started modeling some of my domains/potential code designs in Prolog. I'm not that advanced. I don't really know Prolog that well. But even just using a couple basic prolog patterns to implement a working spec in the 'prolog way' is *unbelievably* useful for shipping really clean code designs to replace hoary old chestnut code. (prolog -> ruby)

I keep wishing for "regex for prolog", ie: being able to (in an arbitrary language) express some functional bits in "prolog-ish", and then be able to ask/query against it. let prologBlob = new ProLog() prologBlob.add( "a => b" ).add( "b => c" ) prologBlob.query( "a == c?" ) == True (not exactly that, but hopefully you get the gist) There's so much stuff regarding constraints, access control, relationship queries that…

Re: Learn Prolog Now (2006)

#37

Post by gota » Wed, Nov 12, 2025, 5:14 PM UTC

DeathArrow wrote: post #20

What kind of problems is Prolog helping to solve besides GOFAI, theorem proving and computational linguistics?

At work, I bridged the gap between task tracking software and mandatory reports (compliance, etc.). Essentially, it handles distributing the effective working hours of workers across projects, according to a varied and very detailed set of constraints (people take time off, leave the company and come back, sick days, different holidays for different remote workers, folks work on multiple stuff at the same time, have gaps in task tracking, etc.).

In the words of a colleague responsible for said reports it 'eliminated the need for 50+ people to fill timesheets, saves 15 min x 50 people x 52 weeks per year'

It has been (and still is) in use for 10+years already. I'd say 90% of the current team members don't even know the team used to have to "punch a clock" or fill timesheets way back.

Re: Learn Prolog Now (2006)

#38

Post by ux266478 » Wed, Nov 12, 2025, 5:15 PM UTC

WillAdams wrote: post #14

qsort wrote: post #7

Earlier quoted context omitted.

Python wins out in the versatility conversation because of its ecosystem, I'm still kinda convinced that the language itself is mid. Prolog has many implementations and you don't have the same wealth of libraries, but yes, it's Turing complete and not of the "Turing tarpit" variety, you could reasonably write entire applications in SWI-Prolog.

Right, Python is usually the second-best choice for a language for any problem --- arguably the one thing it is best at is learning to program (in Python) --- it wins based on ease-of-learning/familiarity/widespread usage/library availability.

Personally I find Python more towards the bottom of the list with me, despite being the language I learned on. Especially if the code involved is "pythonic". Just doesn't jive with my neurochemistry. All the problems of C++ with much greater ambiguity, and I've never really been impressed with the library ecosystem. Yeah there's a lot, but just like with node it's just a mountain of unusably bad crap.

I think lua is the much better language for a wide variety of reasons (Most of the good Python libraries are just wrappers around C libraries, which is necessary because Python's FFI is really substandard), but I wouldn't reach for python or lua if I'm expecting to write more than 1000 lines of code. They both scale horribly.

Re: Learn Prolog Now (2006)

#39

Post by zemptime » Wed, Nov 12, 2025, 5:15 PM UTC

dflock wrote: post #27

zemptime wrote: post #21

Earlier quoted context omitted.

I've wished for the same kind of 'embed prolog in my ruby' for enumerating all possible cases, all invalid cases, etc in test suites. Interesting to know it's not just me!

There are a bunch of libraries that will do this - here's one example of a python one: https://github.com/yuce/pyswip - and a ruby one: https://github.com/preston/ruby-prolog

I did try ruby-prolog. The deeper issue is that its just not prolog. Writing in actual prolog affords a lot of clarity and concision which would be quite noisy in ruby-prolog. To me, the difference was stark enough it wasn't worth any convenience already being in ruby was worth.

Re: Learn Prolog Now (2006)

#40

Post by disambiguation » Wed, Nov 12, 2025, 5:18 PM UTC

I am once again shilling the idea that someone should find a way to glue Prolog and LLMs together for better reasoning agents.

https://news.ycombinator.com/context?id=43948657

Thesis:

1. LLMs are bad at counting the number of r's in strawberry.

2. LLMs are good at writing code that counts letters in a string.

3. LLMs are bad at solving reasoning problems.

4. Prolog is good at solving reasoning problems.

5. ???

6. LLMs are good at writing prolog that solves reasoning problems.

Common replies:

1. The bitter lesson.

2. There are better solvers, ex. Z3.

3. Someone smart must have already tried and ruled it out.

Successful experiments:

1. https://quantumprolog.sgml.net/llm-demo/part1.html