WEBVTT captioned by sachac, checked by bhavin
NOTE Rune
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Hello, EmacsConf. My name is Troy Hinckley, and this is my
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talk on Rune, a Rust implementation in Emacs. We strive to be
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bug compatible with Emacs, so you can use the same Elisp.
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It's still a fairly early stage experimental project, and
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we have some basic things implemented.
NOTE The Emacs core
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Before I get started, I want to talk a bit more
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about what the core is.
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So the Emacs core, it includes the runtime, the interpreter,
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garbage collector, everything used to run the code.
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It includes the GUI. It includes all the data structures.
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If you look underneath all the Elisp data structures,
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there's C code underneath there,
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as well as the auxiliary functions
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of which there's about 1500. In making this talk, I don't
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want to give the impression that I'm saying the core is
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outdated or that needs to be replaced or that it can't be
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evolved on its own, because clearly it has continued to
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evolve. If we look in just the last few years, we can see that
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we've added native compilation, we've added tree-sitter
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support, we've added color emoji, and there's work right
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now to add a new garbage collector to Emacs as well.
NOTE Why create this?
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Why create this project? Emacs has a long history.
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It has a lot of users. It needs to support a big community.
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Because of that, it has to be very conservative
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about what things it can allow into the project.
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Forks like this create an
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opportunity to experiment and try new approaches.
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This is particularly a good use case for Rust because the C core,
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it's pretty well tested. It's been around for a long time.
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A lot of the bugs have been ironed out, but when you're doing a
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new greenfield project, it's very easy to introduce new
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undefined behavior and memory unsafety
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and stuff like that. Rust protects us from most of that,
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but it also gives us the ability to be fast
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and has a strong ecosystem behind it.
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Rust is also really good at multi-threading.
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Their phrase in the community is fearless concurrency.
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They should be able to write concurrent programs without
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having to worry about data races. It's also really high
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performance. It has a really good regex engine. It's known
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for its non-copy I/O as well.
NOTE How does this compare to other projects?
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How does this compare to other
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Rust and Emacs projects, whether there's been a couple? The
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first is Remacs. This project was the first. It took an
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outside-in approach. Basically you could take a C
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function and replace it with a Rust function and build it
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together as one executable. This is pretty easy to do
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because they could both talk over the C ABI. You could
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swap out functions once at a time. They made really good
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progress at first, but eventually they ran into the problem
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that as you get down to the really core parts of it, you can't
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just replace one function at a time anymore, because some of
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that functionality is connected to other things. Like for
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example, you can't replace the garbage collector without
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replacing the entire garbage collection system. So the
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progress really kind of slowed down. Another issue with it
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was, is that they were doing a one-to-one rewrite, so they
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weren't adding any new features or functionality, just
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taking the same code and replacing it in Rust, which doesn't
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add any advantages in and of itself.
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This spawned Emacs-NG, which was kind of the spiritual successor to
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Remacs, where they decided to add new functionality,
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the biggest one being a JavaScript runtime,
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as well as some new renderers to Emacs.
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This is no longer actively developed though.
NOTE Multi-threading
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In this project, one of the big focuses we have is
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on multi-threading. The C core itself is, everything is
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designed around being single-threaded, all the data
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structures and everything like that. Rust has a great
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concurrency story. In Rust, everything is intended to be
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multi-threaded. That doesn't mean that everything has to
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run on multiple threads, but you can't write something that
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is limited to only running in a single-threaded
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environment. So this makes it really easy to use all the
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existing packages and build something that is
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concurrency safe. which is what we've done here,
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and that was relatively easy to do.
NOTE Multi-threading elisp
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But adding it to Elisp is the hard part,
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because we've got to come up with a good model
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for Lisp, and Elisp is just a giant ball
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of mutable state. We need to find some
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way to tame that so we can make workable concurrency
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out of it. There's really two ways you can do this.
NOTE No-GIL method
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One is what I call the no-GIL method.
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This is what Python is doing, where
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you take all of your data structures, you make them
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concurrency safe, and then you just leave it up to the
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programmer to decide what they're going to do with it.
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They've got to build safe abstractions on top of that.
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One of the big downsides with this is that
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it comes with a pretty high cost.
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The last benchmarks I've seen is that by making
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everything concurrency safe in Python, single-threaded
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code is about 20% slower in some benchmarks.
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Since most code is single-threaded, this has a big
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performance impact for most code that isn't taking
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advantage of the multi-threading. The other thing is this
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introduces a lot of nasty concurrency bugs because you can
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have anything mutating any part of the data from any thread,
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even if you can't have memory unsafety per se.
NOTE Actors
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The other option is actors,
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which are a really known way to approach this,
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where you trade some of that flexibility that you get
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with fully concurrent for more control and. Code and
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functions are shared between all the different threads,
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but data has to be passed along channels between different
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actors.
NOTE Multi-threading elisp (functions)
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We want the functions to be shared, and this
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should be pretty easy because we don't mutate functions
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like we do data, except when we do. In Lisp, functions are
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just lists like anything else. So you can mutate them
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just like lists. Even if you're not talking about
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interpreted code, like if you have a native compiled
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function, you can still mutate the constants inside the
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function. For example, here we have a function returns a
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string. We take that string out, we mutate that string, and
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now the function returns a different string. In Rune, we
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enforce that all functions, their constants are
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immutable. You can't mutate the insides of a function. You
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can still swap out functions and redefine them, but you
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can't mutate the inside of a function. This enables them
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to be safely shared across threads.
NOTE Caveats
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However, there are some caveats to this.
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For example, some functions actually do
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need to mutate their own data. The example that we run into is
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cl-generic. It uses a method cache. So it has to be able to
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update that cache. In this case, we just made a special
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case for this particular situation, but we don't know what
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more of these we're gonna run into the future where this is
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needed behavior to be able to mutate a function.
NOTE Multi-threading elisp (data)
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Okay, so functions are pretty easy.
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They just can be shared between
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threads, but data can't be immutable, at least not into the
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model that Emacs currently has. We have two different
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ways to handle this. One is we require whenever you're
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calling some other code in a different thread, you have to
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send all the variables that it's going to need over to that
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thread. This is how you traditionally do inside actors.
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Any data that needs to go to a different actor needs to be sent
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over a channel. It's relatively easy implementation, but
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this is difficult in the Emacs case because everything is
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going to be accessing different variables. That means
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when you call something, you have to know ahead of time, all
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the different variables that are gonna be accessed inside
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that other thread and put those in when you call it.
NOTE Copy values to other threads on demands
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The other option we're using is we're copying values to the
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other threads on demand. If you're running a thread, it
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tries to look up a variable. It doesn't have any value for
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that variable. It will go back and ask the main thread and it
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will copy that value into that thread and it can continue
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execution. This is nice because you can just launch some
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code and it'll take care of handling all the data transfer
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for you.
NOTE Multi-threading elisp (buffers)
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But we don't want to be copying around is buffers,
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because they can be really large. In this case, we have a
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mutex. Each thread could only have one current buffer that
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it has an exclusive lock to. This comes with some
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trade-offs, big one being that if the user tries to access
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some buffer, they want to type something, and a background
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thread is holding onto that buffer, what do we do in that
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situation? And we still need to hold an exclusive lock, even
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if we're only going to read a buffer. If you have multiple
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readers, they each still need to take turns because we can't
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determine if at some point a thread is going to try and mutate
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the buffer. It has to be an exclusive lock. The other issue
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is buffer-locals. This is less of a implementation issue
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as much as it is a technical issue. Because you think about
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when we switch to a buffer, it has some buffer-local data and
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we have some thread-local data. As we go through, we're
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mutating everything. Those can get intertwined and
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pointing to each other. Then we switch away from that
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buffer. We need some quick way to be able to separate those
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out. The buffer-locals can go with the buffer-locals and
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the thread data can stay with thread data and make copies of
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anything that was pointing to the other side. But we don't
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have a good method to determine how to separate those two,
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like what data belongs to this and what data belongs to this,
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so that we can do that quickly. We haven't found a good
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solution to that yet, but it's something we're still
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working on.
NOTE Would this actually be useful?
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The question is, would this actually be
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useful for doing real work inside Emacs? I would say,
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yes, there's a lot of things you can do with this. You could
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handle process output in the background. You can do syntax
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highlighting. You can do buffer search in parallel. You can
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do LSP. You can do fetching your mail in the background. You
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can have a window manager that doesn't block your window
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manager when Emacs is blocked. You could do
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something like a file system watcher that keeps up on files
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without blocking Emacs. This wouldn't be so great for
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building concurrent data structures or operating on
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shared data or building your own abstractions, because of the
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trade-offs that we've made here. Okay. That's talking
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about multi-threading.
NOTE Precise garbage collection
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The other thing we're going to talk
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about is precise garbage collection. In Rune, we have a
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safe, precise garbage collection because of the Rust type
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system. Let's look at what the problem is with garbage
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collection in the first place. Really, the tricky part
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about garbage collection is rooting. How do we find out what
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the roots are? These are all the values that are on the
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stack or inside the registers. In this example here, we
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allocate an object. We call garbage_collect, that object's
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collected, and then we try and return it.
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It's no longer valid.
NOTE How Emacs used to deal with roots
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Let's look at how Emacs used to deal with this
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problem way back in the day. There was a system called gcpro
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or GC Protect, which is basically designed that every time a
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value needed to survive past a garbage collection point,
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you had to try and protect it. In order to do this, you had
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to declare a struct, you had to put a macro around it to root
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the object, and then you had to unroot it when you were done--
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past the garbage collection. Now the value is safe. You
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can see down here, I pulled these eight rules out from a
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really old version of the Emacs manual about all the things
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you had to keep track of when you were trying to use this
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system. All right, so there was a special handling for
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nested GC protects. You had to make sure the memory was
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initialized. You had to make sure that traps couldn't occur
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between allocating and when GC protect would happen. It
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can be tricky because you don't always know when a function
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that's getting called could potentially call garbage
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collection. So if you got something wrong, you also
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might not catch it for a long time because garbage
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collection may only get called one out of 99 times. The other
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99 times is just fine. That one time it happens and you
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can't reproduce the issue. When you do get this wrong and
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some, something doesn't get rooted and it gets
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overwritten, it generally doesn't show up right where the
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problem is. It gets showed up way later when you actually try
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and access the value and the value is invalid. You've got
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to track it back to where that thing did not get properly
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rooted. It's a huge source of bugs and very hard to
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maintain.
NOTE Conservative stack scanning
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Emacs decided to go with a different path,
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which we call conservative stack scanning. Basically,
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the garbage collector just looks at the stack and all the
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registers and any data inside there that looks like it could
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be a pointer, it treats it as a pointer. This is nice because
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you get really easy root tracking,
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but it also comes with some trade-offs,
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mostly that your objects are no longer movable.
NOTE Movable objects
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Why would we want movable objects in Emacs?
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There's a couple of different reasons. One is compaction.
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You can take all your heap, you can pack that on down because
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you can coalesce all your objects together. Another is that
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it's easy to implement generational garbage collection.
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You can just copy everything out of your minor heap into your
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older heap. Really, Emacs is kind of uniquely ideal for
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generational collection, because the typical way we
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interact with Emacs is as a series of commands. You execute
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some command, you'd execute the next command, you execute
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a command. It could be happening every key press, it could be
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happening with M-x. However long that command is, that is
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the ideal length for the minor collection generation, the
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first generation. Because once you're done with that
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generation, anything that's still existing is going to be
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around for a very long time. So that works out really well
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for Emacs. We want to make this a generational collector.
00:11:52.280 --> 00:11:56.199
The other thing is with object layout. We use a lot of lists
00:11:56.200 --> 00:12:00.559
inside Emacs Lisp. Every time you go to the cdr, you've
00:12:00.560 --> 00:12:03.039
got to be chasing a pointer around the heap and following
00:12:03.040 --> 00:12:05.439
that. That can potentially result in cache misses and
00:12:05.440 --> 00:12:08.239
all sorts of other things like that. So it can take a long
00:12:08.240 --> 00:12:12.159
time. It can be quite slow. But if you have the ability to move
00:12:12.160 --> 00:12:16.559
objects, you can just relocate an entire list and lay it out
00:12:16.560 --> 00:12:19.168
in an array right next to each other inside memory.
00:12:19.169 --> 00:12:22.479
So iterating over it is just as fast as iterating over an array.
00:12:22.480 --> 00:12:25.421
But you can only do that if you have movable objects.
00:12:25.422 --> 00:12:28.399
I'll point out here too, that with conservative stack scanning,
00:12:28.400 --> 00:12:31.599
it's not that all objects are immovable. It's only ones that
00:12:31.600 --> 00:12:35.519
are pointed to from the stack or from the registers that have
00:12:35.520 --> 00:12:38.828
to become immovable.
NOTE How Rust makes precise GC easy
00:12:38.829 --> 00:12:41.039
Let's look at how Rust makes precise
00:12:41.040 --> 00:12:44.439
garbage collection easy. Here I have some Rust code to
00:12:44.440 --> 00:12:47.279
show kind of how the lifetime system works and what we call
00:12:47.280 --> 00:12:49.879
XOR mutability, where we can only have one mutable
00:12:49.880 --> 00:12:52.879
reference or multiple immutable references to the same
00:12:52.880 --> 00:12:56.199
thing. Here we declare a vector, we take a reference to the
00:12:56.200 --> 00:12:59.199
first element of the vector, and then we mutate the vector.
00:12:59.200 --> 00:13:02.239
Now this could potentially resize the vector and move it to a
00:13:02.240 --> 00:13:04.919
different location in memory, so that reference is no
00:13:04.920 --> 00:13:07.759
longer valid. The nice thing is, Rust catches this for
00:13:07.760 --> 00:13:10.479
us. It says, hey, this is no longer valid. This reference
00:13:10.480 --> 00:13:14.519
can't survive past when you mutated it. Okay? That's
00:13:14.520 --> 00:13:17.559
exactly what we want for a garbage collector. You can see
00:13:17.560 --> 00:13:19.879
here, we take this in a garbage collection context, we
00:13:19.880 --> 00:13:23.359
create a new context object, we add an object, we call
00:13:23.360 --> 00:13:26.759
garbage_collect, then we try and access that object. It's no
00:13:26.760 --> 00:13:29.199
longer accessible, and Rust will prevent us from trying to
00:13:29.200 --> 00:13:34.839
access that variable. So, how do we solve this? We have a
00:13:34.840 --> 00:13:39.759
root macro. We declared this root macro, it lets us take the
00:13:39.760 --> 00:13:41.759
object and let it live past garbage collection, and
00:13:41.760 --> 00:13:45.319
everything works out. The nice thing is, this root macro
00:13:45.320 --> 00:13:47.799
will get dropped when it's out of scope, so we don't have to
00:13:47.800 --> 00:13:51.519
worry about the un-gc-protect step of this. Statically,
00:13:51.520 --> 00:13:55.799
Rust will verify and tell us any object that needs to be
00:13:55.800 --> 00:13:58.279
rooted. If we try and access it, it'll tell us it's invalid.
00:13:58.280 --> 00:14:00.999
We have this root macro and then we can access it. So in
00:14:01.000 --> 00:14:03.759
that way, we have safe, precise garbage collection without
00:14:03.760 --> 00:14:07.479
any chance of introducing undefined behavior, which is
00:14:07.480 --> 00:14:09.999
really, really powerful. It's really easy because the
00:14:10.000 --> 00:14:13.226
type system will catch it all for us.
NOTE Other Rust niceties: proc macro
00:14:13.227 --> 00:14:15.147
There's some other Rust niceties I want to kind of
00:14:15.148 --> 00:14:16.799
talk through that are useful, but
00:14:16.800 --> 00:14:21.079
are not, you know, star features. One is proc macros. You
00:14:21.080 --> 00:14:23.679
can see up on the top, you can see how you declare a function
00:14:23.680 --> 00:14:27.359
inside the C core. All right. You have to use the macro. You
00:14:27.360 --> 00:14:29.141
have to put the list type, the function type,
00:14:29.142 --> 00:14:30.963
the struct type, the different types of arguments
00:14:30.964 --> 00:14:33.225
or different number of arguments, the doc string,
00:14:33.226 --> 00:14:36.023
and then you can put your argument listing down inside there.
00:14:36.024 --> 00:14:37.984
On the Rust side, we just write this like we would
00:14:37.985 --> 00:14:40.044
any other Rust function. And then we put
00:14:40.045 --> 00:14:41.285
the defun proc macro on there
00:14:41.286 --> 00:14:44.186
and it takes care of everything for us behind the scenes.
00:14:44.187 --> 00:14:46.407
A couple of cool additional things we can do with this
00:14:46.408 --> 00:14:48.727
is that we don't have to make everything just an object.
00:14:48.728 --> 00:14:49.759
We can actually make things
00:14:49.760 --> 00:14:54.239
more specific types. Here we have symbols. As well as
00:14:54.240 --> 00:14:56.279
you can see subfeature, it's an optional parameter, and we
00:14:56.280 --> 00:15:00.919
just make it an option inside Rust and it automatically make
00:15:00.920 --> 00:15:03.599
it an optional inside Elisp.
00:15:03.600 --> 00:15:05.181
This makes them really easy to write.
00:15:05.182 --> 00:15:06.439
I can't take credit for this is because this is
00:15:06.440 --> 00:15:09.119
something that I saw inside Remacs and I stole from them, but
00:15:09.120 --> 00:15:11.439
it makes the functions really easy to call from each other
00:15:11.440 --> 00:15:14.559
and really easy to write as well.
NOTE sum types
00:15:14.560 --> 00:15:18.523
Another thing that's really nice is sum types.
00:15:18.524 --> 00:15:21.039
In the C core, if I wanted to get a
00:15:21.040 --> 00:15:23.759
string out of an object, I would first need to check that it's
00:15:23.760 --> 00:15:28.319
a string and then dereference it as a string. But if it's not a
00:15:28.320 --> 00:15:30.679
string, I may introduce undefined behavior. So in
00:15:30.680 --> 00:15:32.799
complicated code, I have to make sure that I have always
00:15:32.800 --> 00:15:34.959
checked what type it is before I try and dereference that
00:15:34.960 --> 00:15:37.879
type. We don't have to worry about any of that inside Rust
00:15:37.880 --> 00:15:41.319
because we can untag a value and we can use their some types,
00:15:41.320 --> 00:15:44.399
basically create an enum and we can match on what the
00:15:44.400 --> 00:15:47.639
different values can be. Then we only get out the types
00:15:47.640 --> 00:15:50.359
that are viable or are actually there. So we never
00:15:50.360 --> 00:15:52.159
accidentally get something out of an object that we didn't
00:15:52.160 --> 00:15:54.239
mean to, or dereference it as something that doesn't
00:15:54.240 --> 00:15:56.879
really exist. We can just match on it and we can get out the
00:15:56.880 --> 00:16:01.040
values that we need, which is really, really powerful.
NOTE Regex
00:16:01.041 --> 00:16:03.639
So there's some other Rust niceties as well working with here.
00:16:03.640 --> 00:16:07.799
One is the regex engine inside Rust is really fast, high
00:16:07.800 --> 00:16:10.959
performance. We are using that for the Elixir regex
00:16:10.960 --> 00:16:14.879
engine to give it high performance and worst-case
00:16:14.880 --> 00:16:16.051
guarantees.
NOTE Parsers
00:16:16.052 --> 00:16:18.599
The other is that Rust has a lot of really good
00:16:18.600 --> 00:16:21.559
parsers for things like JSON that are no copy parsers that
00:16:21.560 --> 00:16:24.719
are high performance. We can use those inside Rune as
00:16:24.720 --> 00:16:27.209
well.
NOTE Other changes: GUI first, terminal second
00:16:27.210 --> 00:16:29.439
There's a handful of other changes we're working on
00:16:29.440 --> 00:16:33.119
that are not Rust-specific, but we'd like to see. The first is
00:16:33.120 --> 00:16:36.759
being GUI first, terminal second. This means two things.
00:16:36.760 --> 00:16:40.039
First is that we have all of our key bindings. Right now
00:16:40.040 --> 00:16:43.279
inside Emacs, C-i and TAB are bound to the same key
00:16:43.280 --> 00:16:45.039
binding by default, because that's how it works inside the
00:16:45.040 --> 00:16:48.119
terminal. In the GUI, you shouldn't have that limitation.
00:16:48.120 --> 00:16:52.559
The second is that the GUI should not block when Lisp is
00:16:52.560 --> 00:16:55.199
blocked. It should be independent of that. Your GUI can
00:16:55.200 --> 00:16:58.918
still continue to operate when Lisp is running.
NOTE Off-screen cursor
00:16:58.919 --> 00:17:01.279
The other is the ability to have an off-screen cursor
00:17:01.280 --> 00:17:02.699
so that you can be typing on something,
00:17:02.700 --> 00:17:04.319
you can scroll up and down and the point
00:17:04.320 --> 00:17:06.719
doesn't have to follow you where you lose your place where
00:17:06.720 --> 00:17:09.399
you were before. You don't have to intentionally set a mark.
00:17:09.400 --> 00:17:11.199
You can just scroll and then start typing and it'll go back up
00:17:11.200 --> 00:17:13.879
to where it was before, like it works in most applications.
00:17:13.880 --> 00:17:16.304
And this can be optional.
NOTE Image flow
00:17:16.305 --> 00:17:18.079
The other is image flow. We want it
00:17:18.080 --> 00:17:20.879
so that you can easily flow images and you can have large
00:17:20.880 --> 00:17:23.159
images and scroll past them without jumping and you can flow
00:17:23.160 --> 00:17:24.439
text around images.
NOTE Testing
00:17:24.440 --> 00:17:29.799
How are we testing this project? Because there's a lot of
00:17:29.800 --> 00:17:33.159
things that you could get wrong here. One thing we're doing
00:17:33.160 --> 00:17:38.039
is we're using ERT. Emacs ships with over 7,000 built-in
00:17:38.040 --> 00:17:42.879
tests--Elisp tests. We are using this test suite to test
00:17:42.880 --> 00:17:45.079
our project as well. We can kind of use this as a dashboard
00:17:45.080 --> 00:17:47.679
of saying how close are we to getting to parity with GNU
00:17:47.680 --> 00:17:52.319
Emacs. The other thing that we have is a tool called elprop,
00:17:52.320 --> 00:17:55.279
which is an external utility that basically tests for
00:17:55.280 --> 00:17:58.719
correctness. Because really, the correctness of Rune is
00:17:58.720 --> 00:18:00.999
whatever Emacs does, because there's no official spec on
00:18:01.000 --> 00:18:04.079
how things should behave. To do this, we can go look at
00:18:04.080 --> 00:18:07.159
the Rust function signature. We know what the arguments
00:18:07.160 --> 00:18:09.319
are, we know how many they are, and we know what types they
00:18:09.320 --> 00:18:11.679
should be. Given that information, we can generate a
00:18:11.680 --> 00:18:15.279
whole bunch of random functions feeding those types in. And
00:18:15.280 --> 00:18:18.959
then we send a copy over to Emacs, we send a copy over to Rune.
00:18:18.960 --> 00:18:21.679
They each evaluate it and they return the result and we make
00:18:21.680 --> 00:18:23.519
sure the results are the same. Then you do that for
00:18:23.520 --> 00:18:26.199
thousands of different implementations of the function.
00:18:26.200 --> 00:18:29.039
And it helps us find corner cases really easy without having
00:18:29.040 --> 00:18:31.639
to handwrite a whole bunch of different cases to test things
00:18:31.640 --> 00:18:36.344
and say, where are these two functions different?
NOTE Status
00:18:36.345 --> 00:18:39.359
So the current status: we already have a multi-threaded Elixir
00:18:39.360 --> 00:18:42.999
interpreter and bytecode engine inside there. There's no
00:18:43.000 --> 00:18:45.679
actual text editor in there yet, but the primitives are
00:18:45.680 --> 00:18:48.679
there. Like you can insert text, move point around,
00:18:48.680 --> 00:18:52.039
delete text, do different things like that. But we don't
00:18:52.040 --> 00:18:53.679
have a GUI hooked up to different key bindings to actually
00:18:53.680 --> 00:18:58.159
type on. There's just a REPL to operate in. We have about
00:18:58.160 --> 00:19:01.279
250 of the 1500 built-in functions already implemented
00:19:01.280 --> 00:19:04.119
inside there. There's a lot of low-hanging fruit inside this
00:19:04.120 --> 00:19:07.246
area to still be implemented.
NOTE Next directions
00:19:07.247 --> 00:19:07.719
The next directions we're
00:19:07.720 --> 00:19:11.959
working on is we're optimizing the GC. We want to make it
00:19:11.960 --> 00:19:13.839
generational. Like I said, right now, it's just a simple
00:19:13.840 --> 00:19:17.359
semi-spaced copying GC. We want to add a proper GUI. We need
00:19:17.360 --> 00:19:19.599
to implement text properties, overlays, process and job
00:19:19.600 --> 00:19:22.738
control, all that goodness right there.
NOTE How to get involved
00:19:22.739 --> 00:19:25.378
How can you get involved? This is hosted on GitHub.
00:19:25.379 --> 00:19:26.424
You can come on over.
00:19:26.425 --> 00:19:28.639
If you have any ideas about how to implement something or
00:19:28.640 --> 00:19:30.639
something you'd like to see done, go ahead and just open an
00:19:30.640 --> 00:19:32.799
issue so we can have a discussion about it. We've had lots of
00:19:32.800 --> 00:19:34.599
interesting discussions with different people coming in
00:19:34.600 --> 00:19:37.639
to the GitHub repo. If you're interested in contributing,
00:19:37.640 --> 00:19:40.439
the easiest way is probably to run elprop, pick some
00:19:40.440 --> 00:19:43.279
function, run elprop on it. I promise it won't take long to
00:19:43.280 --> 00:19:45.639
find some issues, some discrepancy between Emacs and Rune,
00:19:45.640 --> 00:19:48.959
and that lets you dive into the Rust code and figure out, and
00:19:48.960 --> 00:19:50.879
the C code, and figure out what the difference is between the
00:19:50.880 --> 00:19:53.119
two. or come along and help implement your favorite
00:19:53.120 --> 00:19:55.679
functionality. This has been a really interesting project
00:19:55.680 --> 00:19:58.359
so far, and we've had a handful of different contributors on
00:19:58.360 --> 00:20:01.799
it who just kind of want to learn Rust or get more into
00:20:01.800 --> 00:20:06.000
systems-level programming. Thank you.
