Not a pro at all, but my approach is: Pick a goal, e. g. 90 spm, and a set of constraints: am2, yellow belts, design fits in a square, no logistics bots. Then divide and conquer.

It's pretty similar to software engineering, in a way.

Try to learn something along the way. E. g. I found that it's a ...

I see. And I agree, it's quite an edge case. Thank you for letting me know.

I'm using an assembly machine 2 with two production modules 1. These two modules provide a bonus of 8 %, that's 108/100=27/25.

I've put in the required inputs for 25*27*2=1350 products, and I'm expecting 25*27*2 * (27/25) = 1458 outputs. But I'm only seeing 1457.

As soon as I put in another set of ...

I love that combinators have descriptions built in now. I don't love their UI, though.

To edit a description, a new window is spawned. When clicking anywhere outside of that window, it is closed, and any change is getting discarded, without asking or warning the player.

I have lost edits quite a ...

I've always considered making some "decider compiler" mod that can take some more complex expressions and expands them into decider syntax.


I just wrote a mod that does exactly that. See https://forums.factorio.com/viewtopic.php?p=675725#p675725. Not published yet, currently gauging interest.

I found this mod that allows editing combinator conditions as text.
https://mods.factorio.com/mod/combinator-codify

I used it as a baseline to create my own mod for the DSL above. It's pretty powerful.

Looking at the video can be misleading. Should be looked at in game, stepping through frame by frame.

How many ticks are we talking about here? I've never had the need for a delay of more than two or three ticks.

From the thread here it's hard to judge if there's an actual need for it, or if there's a significant benefit. So I think some examples would help.

What about memory requirements? For ...

I just spent a couple hours coercing Copilot into writing a parser and AST transformer for the decider combinator DSL. I call it decolang .

It can parse expressions like red(T) = 23 or ip > 10 and cp > 4 and (T != 112 or P > 5) .

It also normalizes an expression like P=1 and (X=0 or A=3) into P=1 ...

Also weird: Play time doesn't go up in Steam's Offline mode.

Thank you! This is a good start.

I think this would be a great addition to the documentation at https://lua-api.factorio.com/latest/classes/LuaUndoRedoStack.html then.

The undo queue for a player. The term item_index refers to the index of an undo item in the queue, while action_index refers to ...

Video from OP

[virtual-signal=signal-heart]

Honestly, i would rather the ability to type in a logic statement by hand. But something to make strong up conditions is definitely needed.


That's an interesting idea! I would see that rather in the context of a mod than in the base game, since it's very technical.

But it would be cool to have ...

No, I don't think so. My impression is that currently the API doesn't support Undo in general. It would be nice if this was officially acknowledged.

Oooh, nice! I got it to work. Thank you so much!

Oh, yes, I realized this after reading. But it still gave me a bit of that sinking feeling when I first read it.

The intention was to say "The following might be a terrible idea, but...".

How does it work? Is there any way for mod authors to use it?

Which API calls cause an item to get added to the Undo stack?

This is a terrible idea...

Just a heads up, starting a post in this manner might set the wrong tone. :)

I don't care if it's terrible. The game doesn't seem to offer a clean way of letting mods undo things. The devs give mod authors the silent treatment. So anything that works is a good idea in ...

https://forums.factorio.com/viewtopic.php?p=674901#p674901 doesn't seem to be working. It's a mp4 created by OBS. The local file plays fine in my browser.

Here's the BBCode:

[webm][attachment=0]2025-06-20 17-04-25.mp4[/attachment][/webm]

Couldn't find anything here https://forums.factorio.com ...