I think this is explained in The Power of Prolog[1] that the answers coming from Prolog are not printing text to a terminal, they are valid Prolog terms(/data/code). That's why the result uses the same `;` for OR as code does. Answer (x ; y ; false) is "query can be answered by x or y or no other answer found". (This would let you do meta-programming, reasoning about the results and rewriting the results in a LISPy data-as-code way, if you were more advanced than I am).

Prolog systems do optimisations to jump to the correct answer without searching, if they can, (e.g. database style indexing on the facts and rules) and in those cases there is no code left to search after showing the first answer, no need to prompt the user "should I search for more answers in the remaining code?", and so no need for an output "false" to say "I finished searching and found no more solutions".

[1] https://www.metalevel.at/prolog

In the Scryer Prolog discussions, Alex has shared a few ideas and considerations for possible improvements to the Prolog code, including the use of metaprogramming to automatically generate more general relations:

https://github.com/mthom/scryer-prolog/discussions/3221

I hope for an interesting followup article!

Another very interesting Prolog program by Alex is factgraph.pl:

https://github.com/alexpetros/factgraph.pl

It's a Prolog implementation of the IRS Fact Graph, an application of Law as Code.

So I forked the calculator and added a Prolog wrapper so I could find solutions to battles based on the team of Pokemon that I caught. https://github.com/deosjr/runbuncalc/blob/master/main.pl

My runs died pretty early, but there are some notes here as I was implementing that are fun to read. I implemented each battle as a test case and let my solver find a solution, then amended the plan and commented on what actually happened. For example: https://github.com/deosjr/runbuncalc/blob/master/run10.pl#L2...

    SELECT DISTINCT pokemon, special_attack
    FROM pokemon as p
    WHERE
      p.special_attack > 120
      AND EXISTS (
        SELECT 1
        FROM pokemon_moves as pm
        WHERE p.pokemon_name = pm.pokemon_name AND move = 'freezedry'
      )
      AND EXISTS (
        SELECT 1
        FROM pokemon_types as pt
        WHERE p.pokemon_name = pt.pokemon_name AND type = 'ice'
      );

    SELECT DISTINCT pokemon, special_attack
    FROM pokemon as p
      NATURAL JOIN pokemon_moves as pm
      NATURAL JOIN pokemon_types as pt
    WHERE
      p.special_attack > 120 AND
      pm.move = 'freezedry' AND
      pt.type = 'ice'
    ;

Prolog must be an adult programming language :)

Do you have an Odin tutorial that's as easy to digest?

Sol