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+WEBVTT captioned by sachac and robin
+
+00:00:00.000 --> 00:00:03.839
+Hello everyone. I'm Robin Templeton, and I'm going to talk
+
+00:00:03.840 --> 00:00:07.919
+about Emacs Beguiled and recent progress on the Guile-Emacs
+
+00:00:07.920 --> 00:00:13.919
+project.
+
+00:00:13.920 --> 00:00:16.839
+First of all, if you're not familiar with Guile, it's an
+
+00:00:16.840 --> 00:00:20.239
+implementation of the Scheme programming language, which
+
+00:00:20.240 --> 00:00:24.799
+is a dialect of Lisp, and in the same family as Emacs Lisp, and
+
+00:00:24.800 --> 00:00:28.759
+Guile is GNU's official extension language. The goal of
+
+00:00:28.760 --> 00:00:32.679
+the Guile-Emacs project is to use Guile as the basis for
+
+00:00:32.680 --> 00:00:37.599
+Emacs's Lisp support. It has two main components: a new
+
+00:00:37.600 --> 00:00:41.919
+Emacs Lisp compiler built on top of Guile, and a variant of
+
+00:00:41.920 --> 00:00:45.199
+Emacs in which the built-in Lisp implementation is
+
+00:00:45.200 --> 00:00:50.239
+entirely replaced with Guile Elisp. We expect the
+
+00:00:50.240 --> 00:00:53.439
+combination of these two projects to have several
+
+00:00:53.440 --> 00:00:57.999
+benefits. One is improved performance. Another is
+
+00:00:58.000 --> 00:01:03.839
+increased expressiveness for Elisp and making it easier to
+
+00:01:03.840 --> 00:01:07.839
+extend and experiment with the language. Finally, it
+
+00:01:07.840 --> 00:01:13.079
+will reduce Emacs's reliance on C for two reasons. Guile will
+
+00:01:13.080 --> 00:01:16.959
+be responsible for the language implementation, so Emacs
+
+00:01:16.960 --> 00:01:21.559
+will no longer have to include a Lisp interpreter. It
+
+00:01:21.560 --> 00:01:25.759
+will also become possible to implement much more of Emacs in
+
+00:01:25.760 --> 00:01:30.279
+Lisp than is currently feasible. Of course, this raises
+
+00:01:30.280 --> 00:01:34.119
+the question of why Guile is suitable for this project. And
+
+00:01:34.120 --> 00:01:38.079
+we chose Guile for a few reasons. Guile is primarily a Scheme
+
+00:01:38.080 --> 00:01:41.119
+implementation, but it also has built-in support for
+
+00:01:41.120 --> 00:01:44.399
+multiple languages using its compiler tower. To add
+
+00:01:44.400 --> 00:01:50.079
+support for a new language to Guile, you only have to write a
+
+00:01:50.080 --> 00:01:53.399
+compiler from the source language to Tree-IL, which is
+
+00:01:53.400 --> 00:01:57.439
+essentially a low-level, minimal representation of
+
+00:01:57.440 --> 00:02:02.479
+Scheme. All of Guile's compiler optimizations occur at the
+
+00:02:02.480 --> 00:02:07.599
+Tree-IL layer or lower, so you don't need to worry about the
+
+00:02:07.600 --> 00:02:10.159
+lower-level details of the compiler when initially
+
+00:02:10.160 --> 00:02:14.639
+implementing your language. Guile also has some Lisp
+
+00:02:14.640 --> 00:02:18.879
+features that are very rare in Scheme implementations. For
+
+00:02:18.880 --> 00:02:22.599
+example, it has a nil value that counts as both false and an
+
+00:02:22.600 --> 00:02:27.759
+empty list, just like in Elisp, and it also has a version of
+
+00:02:27.760 --> 00:02:32.319
+the Common Lisp Object System and its metaobject protocol,
+
+00:02:32.320 --> 00:02:37.239
+which is called GOOPS.
+
+00:02:37.240 --> 00:02:42.199
+The idea of Guile-Emacs has a pretty long history, going back
+
+00:02:42.200 --> 00:02:45.319
+at least three decades. There have been about half a dozen
+
+00:02:45.320 --> 00:02:48.519
+previous implementation attempts. But the current
+
+00:02:48.520 --> 00:02:51.519
+iteration began with a series of six Summer of Code
+
+00:02:51.520 --> 00:02:56.279
+internships: Daniel Kraft's in 2009, and then my
+
+00:02:56.280 --> 00:03:02.519
+internships from 2010 to 2014. My basic implementation
+
+00:03:02.520 --> 00:03:06.319
+strategy was pretty straightforward. I implemented a core
+
+00:03:06.320 --> 00:03:09.679
+subset of Elisp, which was enough to run some batch mode
+
+00:03:09.680 --> 00:03:15.399
+programs outside of Emacs. In Emacs, I modified the garbage
+
+00:03:15.400 --> 00:03:19.679
+collector and the data structures for Lisp objects to use
+
+00:03:19.680 --> 00:03:24.679
+their libguile equivalents. I replaced Emacs' Lisp
+
+00:03:24.680 --> 00:03:32.199
+evaluator with the one provided by Guile Elisp.
+
+00:03:32.200 --> 00:03:35.919
+After a little over a year of work, at the end of the 2014
+
+00:03:35.920 --> 00:03:41.079
+internship, I ended up with a fully functional prototype of
+
+00:03:41.080 --> 00:03:46.039
+Guile-Emacs. It used Guile Elisp alone as its Lisp
+
+00:03:46.040 --> 00:03:53.319
+implementation and was completely compatible with Emacs
+
+00:03:53.320 --> 00:03:57.559
+functionality and with external extensions. One caveat
+
+00:03:57.560 --> 00:04:01.399
+was that performance was pretty bad, because I was focused
+
+00:04:01.400 --> 00:04:05.639
+on correctness, as well as ease of integration with the
+
+00:04:05.640 --> 00:04:10.559
+Emacs C code. But it was nonetheless a major milestone for
+
+00:04:10.560 --> 00:04:15.759
+the project. Let's take just a moment to look at
+
+00:04:15.760 --> 00:04:19.599
+Guile-Elisp.
+
+00:04:19.600 --> 00:04:23.879
+For starters, we have access to Guile modules. If we call
+
+00:04:23.880 --> 00:04:26.959
+Guile's <i>version</i> function, we can see that we're running
+
+00:04:26.960 --> 00:04:33.879
+under Guile 3.0. We have access to some of the numeric tower via
+
+00:04:33.880 --> 00:04:41.279
+the arithmetic functions. We also have multiple values. We
+
+00:04:41.280 --> 00:04:45.599
+have to be careful to use Guile's <i>values</i> procedure here, not
+
+00:04:45.600 --> 00:04:48.839
+the CL library's, but you can see that this works properly
+
+00:04:48.840 --> 00:04:52.879
+rather than being an emulation. Finally, we have tail
+
+00:04:52.880 --> 00:04:57.999
+call elimination. Naturally, we're going to use factorial
+
+00:04:58.000 --> 00:05:07.159
+to demonstrate it. If <i>n</i> is zero, return the answer, else
+
+00:05:07.160 --> 00:05:14.199
+recurse with <i>n</i> less one and <i>n</i> times <i>a</i>.
+
+00:05:14.200 --> 00:05:17.119
+Of course, this definition works correctly, but it gets
+
+00:05:17.120 --> 00:05:21.759
+more interesting if we communicate the answer with an
+
+00:05:21.760 --> 00:05:27.759
+error,
+
+00:05:27.760 --> 00:05:32.359
+in order to look at a backtrace. You can see here that there are no
+
+00:05:32.360 --> 00:05:37.839
+calls to <i>fact</i> visible in between the request to evaluate and
+
+00:05:37.840 --> 00:05:42.199
+the error communicating the answer. That's because
+
+00:05:42.200 --> 00:05:53.319
+this tail call has been optimized into effectively a goto.
+
+00:05:53.320 --> 00:05:55.759
+This is essential for any kind of serious functional
+
+00:05:55.760 --> 00:06:00.279
+programming.
+
+00:06:00.280 --> 00:06:05.359
+That's a peek at Guile-Elisp. In 2015, I left university
+
+00:06:05.360 --> 00:06:09.479
+to go work on web technologies, and the project was dormant
+
+00:06:09.480 --> 00:06:14.679
+for a very long time. But that's been changing recently.
+
+00:06:14.680 --> 00:06:17.039
+During the last few months, I've been working with Larry
+
+00:06:17.040 --> 00:06:23.399
+Valkama to rebase Guile-Emacs onto the development branch
+
+00:06:23.400 --> 00:06:28.319
+of upstream Emacs, including the past decade's worth of
+
+00:06:28.320 --> 00:06:33.399
+upstream development. What we've ended up with is a series
+
+00:06:33.400 --> 00:06:38.839
+of rebases onto different versions of Emacs. The older ones
+
+00:06:38.840 --> 00:06:44.239
+tend to work pretty well. The newer ones have increasingly
+
+00:06:44.240 --> 00:06:49.799
+bad problems where they haven't been properly adjusted for
+
+00:06:49.800 --> 00:06:55.599
+changes in the Emacs implementation. But we do have by now a
+
+00:06:55.600 --> 00:06:58.919
+version of Emacs 30 which boots correctly and can be used for
+
+00:06:58.920 --> 00:07:04.959
+interactive debugging, as well as the ability to bisect the
+
+00:07:04.960 --> 00:07:08.919
+revisions of Emacs and find out where regressions were
+
+00:07:08.920 --> 00:07:13.199
+introduced. Our immediate goal is of course to complete
+
+00:07:13.200 --> 00:07:19.719
+the rebase. At the same time, we want to improve Guile Elisp's
+
+00:07:19.720 --> 00:07:22.799
+performance to at least be competitive with ordinary Emacs
+
+00:07:22.800 --> 00:07:29.279
+Lisp. Just to characterize the performance situation,
+
+00:07:29.280 --> 00:07:34.479
+Guile Elisp is usually about half as fast as ordinary Elisp,
+
+00:07:34.480 --> 00:07:37.839
+while Guile Scheme is quite often an order of magnitude
+
+00:07:37.840 --> 00:07:43.319
+faster than ordinary Elisp, and that's based on micro
+
+00:07:43.320 --> 00:07:47.799
+benchmarks like the Gabriel benchmarks. But there's
+
+00:07:47.800 --> 00:07:52.319
+clearly a lot of room to improve our compiler's output.
+
+00:07:52.320 --> 00:07:57.759
+If you want to mark your calendars, we're expecting to have a
+
+00:07:57.760 --> 00:08:04.199
+usable version of Guile-Emacs 30 out sometime next spring. We're
+
+00:08:04.200 --> 00:08:06.799
+also going to put some effort into either extracting old
+
+00:08:06.800 --> 00:08:13.599
+work or doing new work that could be contributed upstream.
+
+00:08:13.600 --> 00:08:17.559
+On the Guile side, we'll probably start out with optimizing
+
+00:08:17.560 --> 00:08:22.839
+the dynamic binding facilities, which are used very seldom
+
+00:08:22.840 --> 00:08:27.199
+in Scheme, but are used all the time in traditional Lisp
+
+00:08:27.200 --> 00:08:31.399
+dialects. On the Emacs side, we'll be working initially on
+
+00:08:31.400 --> 00:08:35.919
+abstracting away the details of the Lisp implementation
+
+00:08:35.920 --> 00:08:39.999
+where they're not relevant. And that will clean up the Emacs
+
+00:08:40.000 --> 00:08:44.279
+code base a bit. It'll make it easier to integrate Emacs and
+
+00:08:44.280 --> 00:08:49.919
+Guile Elisp. It will probably be helpful for anyone who
+
+00:08:49.920 --> 00:08:51.559
+is working on ordinary Elisp on their own.
+
+00:08:51.560 --> 00:08:57.199
+We're also going to be adding new features to Emacs Lisp.
+
+00:08:57.200 --> 00:09:01.639
+We've seen a few of them already. The numeric tower, tail
+
+00:09:01.640 --> 00:09:05.919
+call optimization, Common Lisp compatibility. We're also
+
+00:09:05.920 --> 00:09:10.359
+going to provide access to Fibers, which is a Guile library
+
+00:09:10.360 --> 00:09:14.639
+based on ideas from Concurrent ML that provides much more
+
+00:09:14.640 --> 00:09:17.679
+powerful facilities for concurrent and parallel
+
+00:09:17.680 --> 00:09:20.679
+programming than what Emacs currently offers.
+
+00:09:20.680 --> 00:09:33.759
+This plan meets Guile-Emacs' basic goals, and it's work
+
+00:09:33.760 --> 00:09:36.879
+that we could maybe get integrated upstream in a reasonable
+
+00:09:36.880 --> 00:09:41.799
+amount of time. But it's also worth considering what more we
+
+00:09:41.800 --> 00:09:47.239
+can do, and what effect Guile-Emacs might have on Emacs if it
+
+00:09:47.240 --> 00:09:49.079
+becomes simply Emacs.
+
+00:09:49.080 --> 00:09:54.599
+For context, the amount of C code in Emacs has increased by
+
+00:09:54.600 --> 00:09:58.559
+around 50% in the last decade, and now it constitutes around
+
+00:09:58.560 --> 00:10:06.399
+a quarter of the code base. C can be a bit of a barrier to
+
+00:10:06.400 --> 00:10:13.279
+customizing and extending Emacs. For example, there are
+
+00:10:13.280 --> 00:10:20.439
+about 1500 C subroutines. Around 500 are used in C code, as
+
+00:10:20.440 --> 00:10:26.519
+well as available to Lisp code, and being written in C means
+
+00:10:26.520 --> 00:10:31.519
+that they can't be practically redefined. The use of C can
+
+00:10:31.520 --> 00:10:35.839
+become a barrier to extending Emacs or customizing its
+
+00:10:35.840 --> 00:10:40.479
+behavior. We might consider writing as much of Emacs as
+
+00:10:40.480 --> 00:10:46.039
+possible in Lisp. One way to speed up this process would
+
+00:10:46.040 --> 00:10:52.199
+be to provide a Common Lisp implementation for Guile. Note
+
+00:10:52.200 --> 00:10:56.199
+that between Guile Elisp and Guile Scheme, we have all of
+
+00:10:56.200 --> 00:10:58.839
+the essential ingredients for a Common Lisp environment.
+
+00:10:58.840 --> 00:11:03.279
+We can also share code with other Common Lisp
+
+00:11:03.280 --> 00:11:12.479
+implementations such as SBCL and SICL. Overall, the
+
+00:11:12.480 --> 00:11:15.959
+duration of the project will be better measured in months
+
+00:11:15.960 --> 00:11:19.479
+rather than years, despite Common Lisp's reputation for
+
+00:11:19.480 --> 00:11:23.959
+being a large language. This could have multiple uses, of
+
+00:11:23.960 --> 00:11:29.199
+course. It could be a model for future improvements to
+
+00:11:29.200 --> 00:11:38.399
+Elisp, because Elisp and CL can interact directly without
+
+00:11:38.400 --> 00:11:41.319
+problems. And it would be very easy for Elisp to borrow
+
+00:11:41.320 --> 00:11:45.479
+language features from Common Lisp. But for the purpose of a
+
+00:11:45.480 --> 00:11:49.559
+C to Lisp transition, it would also provide us with instant
+
+00:11:49.560 --> 00:11:52.599
+access to a huge number of high-quality libraries for
+
+00:11:52.600 --> 00:11:58.159
+things that Guile is not necessarily equipped to deal with,
+
+00:11:58.160 --> 00:12:03.879
+such as access to low-level Windows APIs, as well as lots of
+
+00:12:03.880 --> 00:12:08.799
+other libraries, such as interfaces to GUI toolkits for a
+
+00:12:08.800 --> 00:12:12.079
+variety of operating systems.
+
+00:12:12.080 --> 00:12:21.799
+At a certain point, this has technical advantages. If
+
+00:12:21.800 --> 00:12:26.119
+most of Emacs is written in Lisp, then we could consider
+
+00:12:26.120 --> 00:12:30.759
+using Guile Hoot to compile Emacs to WebAssembly, making it
+
+00:12:30.760 --> 00:12:35.159
+available perhaps in web browsers or on systems with the
+
+00:12:35.160 --> 00:12:40.679
+WebAssembly System Interface. But it would also be a great
+
+00:12:40.680 --> 00:12:44.759
+victory for practical software freedom. That's the idea
+
+00:12:44.760 --> 00:12:48.359
+that Freedom One, the freedom to study and modify programs,
+
+00:12:48.360 --> 00:12:52.039
+should not just be legally and technically possible, but
+
+00:12:52.040 --> 00:12:54.719
+should be actively encouraged by our computing
+
+00:12:54.720 --> 00:12:58.959
+environments. Emacs is really one of the archetypal
+
+00:12:58.960 --> 00:13:02.519
+examples of this, but we can and should go further.
+
+00:13:02.520 --> 00:13:10.919
+When Emacs is implemented primarily in Lisp, the entirety
+
+00:13:10.920 --> 00:13:14.599
+of the system will be transparent to examination and open to
+
+00:13:14.600 --> 00:13:20.359
+modification. Every part of Emacs will be instantaneously
+
+00:13:20.360 --> 00:13:23.319
+inspectable, redefinable, and debuggable.
+
+00:13:23.320 --> 00:13:30.559
+This will be a fundamental change in what is possible to
+
+00:13:30.560 --> 00:13:36.159
+do with Emacs extensions. For example, one experiment I'd
+
+00:13:36.160 --> 00:13:40.319
+be interested in is using the Common Lisp Interface Manager
+
+00:13:40.320 --> 00:13:46.479
+as the basis for Emacs's user interface. Screwlisp is
+
+00:13:46.480 --> 00:13:52.879
+giving a talk about McCLIM later today, but for present
+
+00:13:52.880 --> 00:13:55.919
+purposes, just think of it as a super-powered version of
+
+00:13:55.920 --> 00:14:01.279
+Emacs's concept of interactive functions. It would be a
+
+00:14:01.280 --> 00:14:04.799
+pretty long-term project in Emacs as it currently exists,
+
+00:14:04.800 --> 00:14:10.519
+but it would be almost trivial if Emacs were customizable at
+
+00:14:10.520 --> 00:14:11.599
+the lowest layers via Lisp.
+
+00:14:11.600 --> 00:14:19.599
+We'll certainly be looking at the practicality of these
+
+00:14:19.600 --> 00:14:23.839
+kinds of changes as we continue developing Guile-Emacs.
+
+00:14:23.840 --> 00:14:31.719
+Finally, how can you get involved with and support Guile
+
+00:14:31.720 --> 00:14:35.999
+Emacs? One way to help is just by trying it out and letting us
+
+00:14:36.000 --> 00:14:40.519
+know what your experiences are like. There will be a
+
+00:14:40.520 --> 00:14:44.079
+snapshot available on the Codeberg project site of the
+
+00:14:44.080 --> 00:14:48.759
+version that I'm using to give this presentation. It will be
+
+00:14:48.760 --> 00:14:52.719
+available both as a Guix package and as a portable tarball.
+
+00:14:52.720 --> 00:14:58.799
+This will be more interesting as we get closer to a complete
+
+00:14:58.800 --> 00:15:05.479
+rebase. We're also always happy to talk to potential
+
+00:15:05.480 --> 00:15:10.879
+contributors or potential collaborators from other
+
+00:15:10.880 --> 00:15:11.599
+projects.
+
+00:15:11.600 --> 00:15:18.159
+We can always use bug reports, and we're interested in what
+
+00:15:18.160 --> 00:15:21.719
+kind of features people actually want to see in Guile-Emacs.
+
+00:15:21.720 --> 00:15:27.359
+Guile-Emacs is also being developed by a small worker
+
+00:15:27.360 --> 00:15:32.159
+cooperative, so donations are a pretty direct way to
+
+00:15:32.160 --> 00:15:36.039
+support the project. If you do nothing else, I recommend
+
+00:15:36.040 --> 00:15:40.719
+going to the website and subscribing to our mailing lists so
+
+00:15:40.720 --> 00:15:45.879
+that you can keep up with news on the project. If you're
+
+00:15:45.880 --> 00:15:49.239
+watching this at EmacsConf, there will be a Q&A session
+
+00:15:49.240 --> 00:15:57.080
+immediately following this, and thanks for watching!