Programming with GURPS Powers

[Bruno]

If the character has the appropriate abilities to sense a world condition, I would allow Trigger to use those abilities as well, to roughly the same level of precision assuming you had someone with perfect focus concentrating on waiting for the condition or event. Trigger never blinks :)

Trigger would be your core for event-based programming.

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Snatcher isn't the only ability with Side Effects sufficient to display results. I'd go to Illusion first before I'd go to Snatcher for simple display, and Control or TK can rearrange things locally for communications as well. Really, most of the Exotic traits count as Side Effects or external devices for output.

Whatever you do, please please please don't make the perl mistake of letting programmers accidentally redefine system constants.

[dcarson]

Affliction lets you do self modifying code.

[mindbound]

Originally Posted by dcarson

Affliction lets you do self modifying code.

Could you give an example of that?

[johndallman]

Originally Posted by whswhs

Who are you envisioning as carrying out the program? The GURPS character, the player who runs that character, the GURPS GM, or maybe some actual computer running GURPS as its programming language?

The abilities themselves make up the program and it runs when they are activated. This is not remotely sensible character design, it's just a thought experiment.

[Celjabba]

Affliction(avantages: mind control(one command : say "hello world"); target:self only; reflexive; trigger(when hearing "Run");linked);
Jumper(time;fixed target: 10 secondes ago; linked)

[Anaraxes]

Originally Posted by johndallman

The abilities themselves make up the program and it runs when they are activated.

That was my mental image of the question. Hence the sideline about how to "realize" the results of the computation, which otherwise are only taking place in that meta level of ability design and activation. That does have game-world effects, so characters could see the results of their computation in-setting. The programming itself is ability design, but that's also not purely meta. Many settings, as with wizards creating magic items, have the characters doing something corresponding to ability design.

So you could say the program is executing in the meta level, or that it's being executed by whatever property of the game world allows abilities to function in the first place. Electrons in silicon crystals aren't doing computation; they're just blindly following the laws of physics. "Computation" is an effect that emerges from artful arrangement of following those laws and interpreting meaning imposed on the behavior.

[whswhs]

Originally Posted by Anaraxes

So you could say the program is executing in the meta level, or that it's being executed by whatever property of the game world allows abilities to function in the first place. Electrons in silicon crystals aren't doing computation; they're just blindly following the laws of physics. "Computation" is an effect that emerges from artful arrangement of following those laws and interpreting meaning imposed on the behavior.

But properties of the game world cannot carry out any sort of program. It's like saying that if you write down a list of equations on a sheet of paper, they compute something. No, actually, they don't. A human being can look at the sheet of paper, and solve the equations, step by step, and compute something by doing so, and a computer might be programmed to carry out the same steps syntactically. But either the human or the computer is a physical entity that can perform actions. The equations are a set of abstract relationships without agency. And in the same way, if you define a set of abstract concepts for a character or a game world, there is no execution until someone actually plays the game, or runs it.

[Andreas]

You don't need some physical entity carrying out the computations for turing completeness. Turing completeness is a property which a set of rules can have (though I suspect that the GURPS powers rules aren't well defined enough to qualify).

[ericthered]

I think you'd have to set up a specific situation to make things work correctly. I think things get a lot easier if you make the machine composed of several "characters", or even an infinite number of them.



Gurps will handle custom triggers just fine. You need to find a minimal set that will do EVERYTHING you want it to do. Branching is easy-peasy.



You need a way to store a LOT of variables. The classic Turing machine requires one or more "infinitely large" tapes, which actually just means arbitrarily large. GURPS is really going to struggle with this, without slapping some cosmic modifiers that may not even be RAW: it really doesn't like infinities. GURPS has LOTS of variables, but I think the best way to store data is in attributes, boosted or lowered by afflictions.



You need a "clock", something that will keep the triggered actions coming, and move either your "CPU" or your variables around so they can interact with each other. Affliction is probably your best core for this, but you'll need some sort of mechanism to put the CPU and what its reading next to each other.



The loop behavior is emergent from the above three.



The simplest way to show it can be done is to use the classic Turing machine. This will require an infinite "tape", or ordered list of symbols that can be moved around (it moves, or the thing reading it moves) and its symbols changed, plus a "Head" that can track a number of states, change the symbols on the "Tape", and have a location on the tape.



The "Tape" can be finite if we have a way to extend it arbitrarily. this is the part I'm struggling with. We can store, read, and modify values using afflictions and detect. I just need a way to create characters ad naseum.

[mindbound]

Several characters forming a "machine" might work in some situations but I'd rather not focus on that primarily, since my goal is not so much recreating the theoretically pure model of Turing machine with GURPS powers as creating some "programmable" GURPS powers (which in-game would be represented by autonomous subroutines, daemons, tulpas, or what have you, just like Modular Abilities can represent a number of slot-like things) that could more or less reasonably be used in an actual campaign, possible clunkiness of the system notwithstanding.