path: root/2023/captions/emacsconf-2023-cubing--speedcubing-in-emacs--vasilij-wasamasa-schneidermann--main.vtt

WEBVTT captioned by sachac, checked by sachac

NOTE Introduction

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Hello, everyone, and welcome to Speedcubing in Emacs.

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First of all, a little bit about myself.

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My name is Vasilij Schneidermann. Online, I go by wasamasa.

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I'm 31 years old. I work in information security,

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and I do consulting and hacking

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and stuff like figuring out

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how to break into other people's computers

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and how to secure their systems basically.

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You can reach me by email.

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I do have a self-hosted code repository thingy going on.

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I have a blog, and you can find me

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in some other places online, like IRC for example.

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So about the talk itself,

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I used to be into the Rubik's cube when I was in school.

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I forgot about it, though,

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because these cubes were not very good.

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Recently I did find some cheap looking cube at a shop.

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Did not pay terribly much for it.

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It was so, so much better than my old cube,

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it was unreal.

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This motivated me to get back into

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this really weird kind of hobby.

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For this, you need to be good at producing

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a truly random scramble

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and timing your attempts to get any better at it.

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There is, of course, existing software

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to do the scrambling for you and the recording

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and the timekeeping and such,

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but all the good options seem to be either web or mobile,

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for example the cstimer software

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or the twisty-timer app on Android.


NOTE Cubing in Emacs

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To my surprise, I did not find a single decent option

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inside Emacs, so this is basically a case study

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how to do better. For this, I wanted to make use of

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all the cool new Emacs features that appeared,

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like the SVG library; Transient,

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the library used for the Magit-style interfaces;

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and the recently added sqlite-mode.

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And most importantly it was about having fun.

NOTE Prior art

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So here's a full list of prior art,

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I will not go into detail about this,

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but basically we have things solving

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very different parts of this,

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but not all of it. For example: we have several,

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we have a timer. We have several solvers.

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We have some scramblers.

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We have some whole-cube simulators, including a 3D one.

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We have something for making it easier

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to enter your algorithms in the notation.

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But nothing that does all of those things in one package,

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which kind of surprised me.

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So I present the `wca-prep` package.

NOTE The name

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So the name, I found it difficult

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to come up with a good name and so I looked

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and I saw, well there's this World Cube Association

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that holds these competitions where you compete.

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They do this for the Rubik's cube

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but also a few others,

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so there's like a standardized list

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of events they have for this.

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There is a standard notation for this

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and rules and everything.

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And the goal of my package is basically

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to help prepare myself for such a competition

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and in fact a week ago I went to my first one

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which was wild, but pretty cool.

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So for this reason I chose this name wca-prep,

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because it helps me prepare for this kind of competition

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and this limited the scope significantly,

NOTE What's in wca-prep

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I have a scrambler, visualization of the scramble,

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timer, and statistics.

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I excluded pretty much everything else I've seen.

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For this reason, I only tried to focus on

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some very basic puzzles I can solve comfortably,

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and did not want to do anything else

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that may complicate things significantly.

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No other kinds of puzzles, no simulation, no solving,

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no exotic events, and no specialized scrambles

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that are only good for practicing specific algorithms.

NOTE Demo

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So at this point the organizer should hopefully show

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a small video I've prepared, a one minute video showing how

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I actually use this to solve a cube and to time my solve.

NOTE Challenges: Representing the cube

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Okay, so building this thing, there were several challenges.

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The first one was how do I even represent

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the state of a Rubik's cube.

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For this there are many possible representations,

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no obvious best solution.

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I did not, well, what helped me was that

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I did not have to programmatically solve this thing,

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so I picked the easiest possible representation

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which is just an array of every single facelet.

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For a 3x3 cube you have 9 facelets on one side,

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so times 6 sides you would have 54 elements in this array.

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So with this representation, it's very simple,

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but it's kind of weird to do scrambles with this.

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But otherwise, it worked very, very well.

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In the future, I plan to learn some group theory,

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pick a better representation

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and do this in a much, much more elegant way

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without compromising speed too much.

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Yes. Once I had the representation,

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the scrambling itself should not be too hard.

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For this, it's important to consider that basically

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if you do a face turn

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you end up swapping some facelets with other facelets,

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that's the easiest way to think about this.

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To determine which one goes into which one's position,

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it was pretty confusing to figure this out.

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For this I went through a few papers,

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and I found one which suggested

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to just build a cube out of paper,

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number every facelet, and turn it

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and keep track of which facelet moved into which position.

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And programmatically, the `cl-rotatef` macro

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was very, very useful for doing this kind of

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in-place swapping you need for this operation.

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So in the future, group theory would hopefully

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make this a bit less awkward.

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Here's a photo of this paper cube I made

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along with a real cube. As you can see

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mathematically speaking, they are the same thing,

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they just look very, very different.

NOTE Scrambling

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So the scramble algorithm itself,

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I pondered how this would even be done. In the competitions,

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They do this in a very, very elaborate way.

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They generate a random cube,

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they try to solve it, and if it's solvable

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they use these solution moves

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to turn into a scramble basically.

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And they also make sure to canonicalize the moves,

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so if you have subsequent moves that can be simplified,

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they do simplify these as much as possible.

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For example,

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if you have two subsequent rotations in one direction,

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it's turned into a different kind of rotation,

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so 90 and 90 equals 180.

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And the other Elisp scramblers I looked at,

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they generate random moves.

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Some of them do canonicalize. Not all of them.

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This one tries to do the best low-fi thing,

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that is, generating random moves,

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canonicalizing and repeating

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until enough have been generated.

NOTE Visualization

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For the visualization I had to figure out

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something else too complicated.

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For this, I tried to figure out

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where every facelift would end up in the puzzle view

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when you would unfold it.

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And for this, I did not consider the facelet orientation.

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This may be important later for some other puzzles

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where you can end up with very twisted faces,

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but for simple cubes, it's not a problem.

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My initial prototype used colored text,

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but later, I used the SVG library.

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It turned out to be easy enough to use, actually.

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Currently, I have hard-coded face-color mappings,

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but I plan to replace this so that theming is possible.

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For example, if you happen to have a cube

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that does not have the same color mappings as I do,

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then you should be able to fix this.

NOTE UI with Transient

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Next challenge was to build

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a beautiful intuitive UI with Transient.

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The reason why I chose this is

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because it would be self-documenting and Magit-style,

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and everyone knows how Magit works basically.

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Since Transient has become part of Emacs,

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there is really no reason to not try it out.

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The problem was documentation is difficult to understand.

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It's very abstract and high level,

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and it's hard to figure out. "Okay,

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I want to do something,

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how am I supposed to do this?"

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I did find transient-showcase, which has lots of examples,

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but they don't really feel finished

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and not realistic enough.

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When I tried to use the package,

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I got plenty of unhelpful error messages

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when using it incorrectly.

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I did manage to figure it out,

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but I plan to find more actual examples of it,

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to have an executable reference basically

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and try to improve my use of it.

NOTE Book-keeping with SQLite

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For the book-keeping, I used SQLite.

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This is a very recent addition to Emacs,

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it only appeared in the current major version.

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It's still very early days.

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I found some oddities, one of them turned out to be

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a bug in the transaction macro.

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Like basically, if you do an SQL transaction

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and an error happens, then every helper I found

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does a rollback on an error.

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But this one did not. It actually committed on an error,

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and this was very weird to figure out.

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I reported a bug. Eli was nice enough to send me a patch.

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We did some patch review,

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and he ended up fixing it properly.

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So yes, there's still a lot to be done there, and yeah,

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the API is very basic.

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You don't have convenience helpers

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like fetch the first row or fetch the first value

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or anything, but they're easy enough to write yourself.

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And the biggest challenge with this bookkeeping part

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was figuring out a decent schema,

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like how to organize data correctly

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so that it would not be awkward to manipulate.

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And with this, you can finally build a package

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that remembers its state properly

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and don't have to run into foot guns

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with Lisp-style serialization, deserialization.

NOTE Conclusion

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So yes, that concludes it so far.

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So what did I learn from this exercise?

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Well, there are still plenty of packages

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for Emacs to be written.

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If you think everything you can think of

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or you need has already been written, well, guess what?

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No.

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These are still plenty of specialized things

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that could need your help.

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These cubes do not require advanced mathematics,

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contrary to what you may think.

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Yes, you can apply advanced mathematics to them

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if you want to, but you don't have to.

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What surprised me about this is basically group theory.

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I've heard of it before.

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It seemed to be a meme, basically,

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because it has been like mostly Haskell people

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being very excited about this

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and it seemed kind of, like, divorced from reality, basically.

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But this puzzle, it actually proves that yes,

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it has its use.

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It definitely has.

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You just have to find the right problem matching it,

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and yeah.

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So yeah, once I understand it better,

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the topic, I expect to write better code.

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These new Emacs features, they work well enough.

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There are some rough edges.

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They definitely need more testing.

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So please, please, everyone,

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if you write Elisp, please try SQLite or Transient

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or anything else that looks cool and shiny.

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Report bugs.

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Find ways to improve them, anything. And yeah,

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I'm sure that if we do this,

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then Emacs will continue to get even better.

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So yeah, what's next for this package?

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Well, I could... There are lots of obvious UI improvements

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and testing to be done.

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I basically want to reach feature parity

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with the twisty-timer app, which this is very much inspired by.

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I want nice-looking stats like graphical ones

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instead of just a simple list of times.

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And I want support for more puzzles, of course,

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not just the simple cubes,

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but as I progress learning these puzzles,

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I want to have Emacs supporting me for this.

00:13:22.520 --> 00:13:26.879
But generally, it's a very open-ended package.

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And this concludes the talk.

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Thank you very much.