A Primer on Logic Programming

https://www.juxt.pro/blog/logic-primer/

by refset • 3 years ago

117 7 3 years ago

juxt.pro

2-718-281-828• 3 years ago

aren't predicates in prolog always starting with a lower letter and only variables with a capital letter?

gorkempacaci• 3 years ago

Yes. Also, in the ancestor predicate, the arrow should be in the other direction.

maweki• 3 years ago

Yeah, we can't distinguish the arguments. Can't have a parent named X, I guess.

aarroyoc• 3 years ago

You can, you just need to quote it in single quotes: 'X'.

dannymi• 3 years ago

Just a heads-up to the author:

Ancestor(X, Y) → Parent(X, Y) ∨ (Parent(X, Z) ∧ Ancestor(Z, Y)).

That's a bug. The arrow needs to go to the left. Also, then, you can also opt to dispense with the disjunction and just use first-order logic normally.

    Ancestor(X, Y) ← Parent(X, Y).
    Ancestor(X, Y) ← Parent(X, Z) ∧ Ancestor(Z, Y).

timClicks• 3 years ago

Introductions to Prolog seem to suffer the "draw the rest of the fucking owl" problem. There's a huge gap from the introductory examples to building real projects.

What I would love to see more of is how to embed a prolog interpreter into a wider program, using the source program's data as the database, then prolog (or perhaps datalog) as an advanced query engine or rules engine.

ralphc• 3 years ago

Tau Prolog embeds prolog into JavaScript. miniKanren embeds logic programming into Scheme. disclaimer, I haven't used either of these.

A Primer on Logic Programming

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