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The Simplicity of Prolog

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Re: The Simplicity of Prolog

#91

Post by horsh1 »

upghost wrote: post #23
GregDavidson wrote: post #7

I have a long standing love affair with Prolog and frustration for its failure to grow. Prolog has poor features for abstraction and is actually not declarative enough! Prolog's limitations can be great for starting to get the paradigm but then you hit a wall. (Kind of like standard Pascal!) Mercury and Curry fix some of these limitations as does miniKanren. Integrating CLP is important yet so far always clumsy as st…

Respectfully have to disagree. Prolog has the best features for abstraction of any language I've used, I suspect it may be near an optimal fixed point for metaprogramming expression[3]. I will say the other side of that wall is breathtaking. Also not sure what you mean, CLP is a first class consideration in many Prologs, esp Scryer Prolog. Check these crazy demos out: [1] https://youtu.be/h5Xy4YjCZxM [2] https://yout…

You have "Rows" repeated eight times in this short snippet. You have all the rest of your variables as two letter names. It feels low level, almost like Fortran.

Re: The Simplicity of Prolog

#92

Post by UltraSane »

2-3-7-43-1807 wrote: post #81
UltraSane wrote: post #70

Earlier quoted context omitted.

Have you tried Datomic?

no. https://github.com/Datomic/codeq : last update to that repo was 12 years ago. it's JDK which I find unappealing. also, how close is it to Datalog? https://github.com/gns24/pydatomic : last update 11 years ago. and that's representative of pretty much anything regarding Datalog. So, I'll just stick to Prolog then. --- have you? would you recommend it?

I tried using Datomic Pro for a CMDB. I liked how logical queries were but I ended up going with Neo4j instead because finding paths between two nodes is incredibly useful in IT.

https://central.sonatype.com/artifact/com.datomic/local/1.0....

Re: The Simplicity of Prolog

#93

Post by upghost »

2-3-7-43-1807 wrote: post #81
UltraSane wrote: post #70

Earlier quoted context omitted.

Have you tried Datomic?

no. https://github.com/Datomic/codeq : last update to that repo was 12 years ago. it's JDK which I find unappealing. also, how close is it to Datalog? https://github.com/gns24/pydatomic : last update 11 years ago. and that's representative of pretty much anything regarding Datalog. So, I'll just stick to Prolog then. --- have you? would you recommend it?

Ok just to clarify, Datomic is a Clojure thing. It is free to use but closed source. It is an excellent database that is used, owned, and financed by Nubank, the largest and most rapidly growing bank in Brazil.

It is not Datalog syntax but heavily inspired by Datalog.

I'm throwing this in here just for clarification, I don't want to see Datomic as collateral damage in this conversation.

Re: The Simplicity of Prolog

#94

Post by simplify »

coliveira wrote: post #35
agumonkey wrote: post #28

Earlier quoted context omitted.

one example that changed my view of prolog was http://faculty.cooper.edu/smyth/cs225/ch7/prolog.htm (a toy compiler in prolog)

And this is nothing new. People already knew how to write compilers in Prolog (easily) in the 90s. The problem with Prolog is that it requires a change in the way you think about problems, to a more declarative way. Programmers are in general not willing to do this since the result will be not as performant as what they can do with C. There must be a revolution in programming education and tools before people fully u…

Something doesn't have to be new to be valuable (XKCD "Ten Thousand" et al). A revolution starts with inspiration.

Re: The Simplicity of Prolog

#95

Post by YeGoblynQueenne »

jodrellblank wrote: post #82
YeGoblynQueenne wrote: post #53

Earlier quoted context omitted.

>> Code might say "connect_to_mongodb()" and you don't have mongodb in your system so you cannot run it, but you can read the code in as data and it will parse, just like reading in JSON which has a string mentioning some library you don't have; you can still introspect it and write reports like "what names does this data reference?", you can transform it and export it, or pass it through untouched. With SWI's new do…

> " cardinal sin of breaking portability. Basically every Prolog ever does that. Every single one. " Indeed; still Markus Triska speaks positively about, and recommends, different Prolog systems. He seems to prioritise things above ISO purity, and is not king of the hill of Scryer Prolog[1], he doesn't comment like others who act as if "the village and city can burn to the ground for all I care, heresy against ISO Pr…

The lack of portability is a bad problem in the Prolog world and it has bit me a few times, but surely the solution is for all the implementers to work together, rather than engage in petty feuding.

But the biggest problem of the Prolog community is what I pointed out above: there's very few of us and the field isn't really growing much.

:(

Re: The Simplicity of Prolog

#97

Post by YeGoblynQueenne »

lionkor wrote: post #11

How can I use Prolog to actually get something done, other than academic tasks? Say I want to use it as a database query language, presumably that's not going to happen, right?

>> How can I use Prolog to actually get something done, other than academic tasks?

Choose the task, download Prolog and start coding. That's, generally, how you "get something done".

As to using Prolog as a database query language, I'd say that's like using a piano as a lawn ornament, but you can certainly replace a traditional relational DB with Prolog. The SWI-Prolog website does that and the developers explain how to do it in this article:

Can I replace a LAMP stack with SWI-Prolog?

https://www.swi-prolog.org/FAQ/PrologLAMP.md

And here's some more about using Prolog for good, old-fashioned, web development, in the sense of creating sites that run on the web and have visitors etc etc, particularly the SWI-Prolog website itself:

Eat Your Own Dog Food

https://www.swi-prolog.org/dogfood.html

Re: The Simplicity of Prolog

#98

Post by upghost »

GregDavidson wrote: post #73
upghost wrote: post #23

Earlier quoted context omitted.

Respectfully have to disagree. Prolog has the best features for abstraction of any language I've used, I suspect it may be near an optimal fixed point for metaprogramming expression[3]. I will say the other side of that wall is breathtaking. Also not sure what you mean, CLP is a first class consideration in many Prologs, esp Scryer Prolog. Check these crazy demos out: [1] https://youtu.be/h5Xy4YjCZxM [2] https://yout…

Prolog predicates are not first class values. Data structures are not abstract. Compare both with any modern lisp or better with functional languages. Mapping and filtering is awkward. Arithmetic is awkward. Indexing and search strategies are not under programmer control. Modes are awkward. Cut and dynamic assert of global facts are abominations which undermine logical reasoning. Prolog programmers often write metaci…

A lot of these comments don't make any sense to me.

> Prolog predicates are not first class values.

Predicates are trivially called, even as variables, with the `call/N` metapredicate.

> Mapping and filtering is awkward

In what sense? The declarative semantics...?

> Arithmetic is awkward

In what sense...? Have you seen clpz?

> The CLP examples aren't integrated with Prolog's Horn clause resolution model

In what sense...? clpz and clpb do this magnificently.

> Indexing and search strategies are not under programmer control.

Most ship with SLG resolution or you can write your own resolution strategy with a simple metainterpreter as an intermediate exercise -- but SLD resolution is already pretty good. In general not needing to think about the indexing and search strategies are a highlight of the declarative semantics of Prolog, its odd to see someone with a "long standing love affair with Prolog" list this as a drawback.

> Modes are awkward.

Modal programming is a defining feature of Prolog. Tell me more about this "long standing love affair", again?

> I've been an enthusiastic Prolog programmer since the mid 1980s

If you are still struggling with mapping, filtering, arithmetic, `call/N`, and CLP in Prolog after nearly 45 years of "enthusiastic" programming, I'd highly recommend checking out Triska's Power of Prolog videos for some guidance, I think you will find them very illuminating.

https://youtube.com/@thepowerofprolog

Re: The Simplicity of Prolog

#100

Post by fithisux »

GregDavidson wrote: post #7

I have a long standing love affair with Prolog and frustration for its failure to grow. Prolog has poor features for abstraction and is actually not declarative enough! Prolog's limitations can be great for starting to get the paradigm but then you hit a wall. (Kind of like standard Pascal!) Mercury and Curry fix some of these limitations as does miniKanren. Integrating CLP is important yet so far always clumsy as st…

Very thankful for listing here.

I think Picat also falls in this category.

Also Racket and Julia have a Prolog implementation.

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