It makes the same analogy that Prolog (or logic programming languages in general) have been strongly influenced by the resolution algorithm. In practice that means that if you write a non-trivial program, if performance is not right you'll need to understand the execution model and adapt to it, mainly with the pruning operator (!). So while the promise is to "declare" values and not think about the implementation details, you're railroaded to think in a very specific way.
I personally found that frustrating to find good solutions essentially unworkable because of this, in comparison with either imperative or functional paradigms that are significantly more flexible. As a result, Prolog-style programming feels limited to the small problems for which it is readily a good fit, to be integrated into a general program using a general-purpose language. I may be wrong on this, but of the 50 people that learned Prolog around the same time as me, none kept up with it. Meanwhile, other niche languages like Ocaml, Haskell and Scheme had good success.
Rethinking the language foundation could remove these barriers to give the language a broader user base.
The argument is basically that Prolog is not 100% declarative and that if we jump through a few hoops, and translate it all to functional notation, we can make it "more declarative". But let's instead compare the incomplete declarativeness of Prolog to a fully-imperative, zero-declarative language like Python or C#. We'll find I believe that most programmers are perfectly fine programming completely non-declaratively and don't have any trouble writing very complex programs in it, and that "OMG my language is not purely declarative" is the least of their problems. I hear some old, wizened nerds even manage to program in C where you actually can drop to the hardware level and push bits around registers entirely by hand O.o
I was quite hooked to Prolog in a previous life. Then the limiting factor was the tooling, for really practical use.
Could you tell a bit about your Prolog environment?
https://www.swi-prolog.org/PceEmacs.html
I suppose it is a bit spartan, but it has a ton of functionality that I find indispensable [1]. For example, when I place my cursor on a variable in the editor it highlights all the variables that unify with it in the same clause, and it will highlight singleton variables in a different colour so you can catch errors caused by typos easily. It is also aware of things like imported predicates, undefined or dynamic predicates, multi-file predicates etc, and will highlight them accordingly. It has some (limited) auto-complete and code-expansion etc. and a status line that gives you very good information about the kind of term you have your cursor on - where it's defined if it's a predicate, its name and arity and how many clauses etc, basically much of the information you can get from querying the program database with various program inspection built-ins. Some of my colleagues use VS Code to write Prolog instead and I keep shaking my head and grumbling about the errors they keep making that they wouldn't if they used the SWI-Prolog IDE instead. Kids, these days. In my youth, we wrote all our Prolog on Notepad! And compiled on Dos!
(nope. never)
SWI also has a graphical debugger, which however I never use:
https://www.swi-prolog.org/pldoc/doc/_SWI_/xpce/prolog/lib/g...
I know some people swear by its name but I prefer the textual debugger. Again this one looks a little spartan :)
More goodies in SWI: cross-referencer:
https://www.swi-prolog.org/gxref.md
And profiler:
1 ?- profile(between(1,10,_)).
=====================================================================
Total time: 0.000 seconds
=====================================================================
Predicate Box Entries = Calls+Redos Time
=====================================================================
between/3 1 = 1+0 0.0%
true.
________________________
[1] You can customise the IDE colours too. There's a dark theme:
https://www.swi-prolog.org/pldoc/man?section=theme
There's some screenshots here:
https://swi-prolog.discourse.group/t/questions-about-ide-the...
I did an MSc in data science first, then started a PhD to study Inductive Logic Programming (ILP), which is basically machine learning × Prolog (although there's also ASP ILP these days). I got my PhD last summer and I'm now doing a post-doc on a robotics project with Meta-Interpretive Learning (MIL), a recent form of ILP. Here's my latest publication:
https://github.com/stassa/ijclr_2024_experiments
Which is still a bit proof-of-concept. We're still at the very early stages of practical applications of MIL and so there's a lot of foundation work to do. Bliss :)
Thanks for the pointer :)