This is a repo where I learn how to write in Prolog by writing programs to solve the daily puzzle game Murdle.

The file murdle.pl has rules we use in figuring the solution, as well as facts about the various suspects and weapons who may appear in each puzzle. I believe that if a particular suspect appears in a puzzle, they'll always have the same biographical facts. Each day, I only add enough facts to solve a particular day's challenge, but eventually, the database of facts will be complete (if the facts work like I think they do).

Then the various murdle-YYYY-MM-DD.pl files have the particular clues to solve a particular day's puzzle.

To run this, start up your prolog interpreter (I'm using SWI-Prolog, but I'm trying to maintain compatibility with GNU Prolog).

From the ?- prompt, load the day's puzzle and run the appropriate one of these commands:

• murdler(P, W, L). to solve the puzzle. P will be the suspect, W will be the weapon, and L will be the location.
• If it's a puzzle that has motives, use murdler(P, W, L, M), and M will be the motive.

Here's a sample run.

GNU Prolog 1.5.0 (64 bits)
Compiled Jul  8 2021, 09:35:47 with clang
Copyright (C) 1999-2024 Daniel Diaz

| ?- ['murdle-2025-05-04'].
compiling /path/to/murdle/murdle-2025-05-04.pl for byte code...
/path/to/murdle/murdle-2025-05-04.pl compiled, 48 lines read - 7630 bytes written, 4 ms

(2 ms) yes
| ?- murdler(P,W,L).
compiling /path/to/murdle/murdle.pl for byte code...
/path/to/murdle/murdle.pl compiled, 50 lines read - 8507 bytes written, 3 ms

L = cafeteria
P = president_amaranth
W = bottle ? ;

(417 ms) no

When there comes to be a puzzle where we also have to solve the motive, I'll have to make it be murdler(P,W,M,L). to solve the person, weapon, motive, and location.