path: root/2025/captions/emacsconf-2025-modern--some-problems-of-modernizing-emacs--eduardo-ochs--main.vtt

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NOTE Introduction

00:00:00.000 --> 00:00:02.359
Hi, my name is Eduardo Ochs,

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and this is my video for the EmacsConf 2025.

00:00:06.640 --> 00:00:09.799
Its title is Some Problems of Modernizing Emacs,

00:00:09.800 --> 00:00:12.839
and that is the same title as a video

00:00:12.840 --> 00:00:16.199
that I tried to record in March.

00:00:16.200 --> 00:00:19.879
But my video from March had a good "beginning" and a bad "rest",

00:00:19.880 --> 00:00:23.759
and I thought, I can't release that because the rest is very bad.

00:00:23.760 --> 00:00:27.919
I need to replace... to re-record the last part of the video.

00:00:27.920 --> 00:00:29.759
But I never did that.

00:00:29.760 --> 00:00:33.199
So this video is going to be the first 12 minutes

00:00:33.200 --> 00:00:37.959
of that other video, with another ending.

00:00:37.960 --> 00:00:41.439
And in this other ending, I'm going to show some things

00:00:41.440 --> 00:00:46.639
that are very easy to test. And, if people are interested,

00:00:46.640 --> 00:00:51.799
then the rest of the old video will make more sense.

00:00:51.800 --> 00:00:55.059
Anyway, let me start.

00:00:55.000 --> 00:00:57.000
Hi! My name is Eduardo Ochs. I'm the

00:00:57.000 --> 00:01:00.000
author of an Emacs package called eev and

00:01:00.000 --> 00:01:03.000
the title of this video is

00:01:03.000 --> 00:01:05.000
"Some problems of modernizing Emacs".

NOTE The main themes of this video

00:01:05.000 --> 00:01:08.000
Here is a summary of the main themes

00:01:08.000 --> 00:01:10.000
of this video. I'm going to talk mainly

00:01:10.000 --> 00:01:12.000
about these four things here. The first

00:01:12.000 --> 00:01:15.000
one is that Emacs has changed a lot in its

00:01:15.000 --> 00:01:18.000
recent versions, and now it has lots of

00:01:18.000 --> 00:01:21.000
types... so if we want to look under the

00:01:21.000 --> 00:01:24.000
hood and to understand what Emacs

00:01:24.000 --> 00:01:27.000
really does we are going to stumble on

00:01:27.000 --> 00:01:30.000
lots of types... and the

00:01:30.000 --> 00:01:34.000
current tree of classes and types

00:01:34.000 --> 00:01:37.000
looks like this... that is,

00:01:37.000 --> 00:01:46.000
is quite big.

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The second theme is that people used

00:01:49.000 --> 00:01:53.000
to say things like "Anyone can learn Lisp

00:01:53.000 --> 00:01:56.000
in one day"... I'm going to explain

00:01:56.000 --> 00:02:01.000
this quote, and I'm also going to show

00:02:01.000 --> 00:02:04.000
that now this is gone... anyway. This is a

00:02:04.000 --> 00:02:08.000
very short summary... details soon.

00:02:08.000 --> 00:02:10.000
I will also show how to display

00:02:10.000 --> 00:02:13.000
better "inner views" of Emacs objects...

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I'm going to define what is an inner view,

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of course.

NOTE Inner views of Emacs objects

00:02:18.000 --> 00:02:20.000
The main trick is that we are going

00:02:20.000 --> 00:02:24.000
to use one of the ways of displaying

00:02:24.000 --> 00:02:29.000
internal objects, that is the `cl-print`

00:02:29.000 --> 00:02:32.000
family of functions, for example,

00:02:32.000 --> 00:02:35.000
`cl-prin1-to-string`, and here are some

00:02:35.000 --> 00:02:37.000
examples of the kind of output that we

00:02:37.000 --> 00:02:38.000
are going to see...

00:02:38.000 --> 00:02:44.000
for example, if we run these two lines

00:02:44.000 --> 00:02:47.000
here the first line defines a function `foo`

00:02:47.000 --> 00:02:52.000
and the second line sets `o` to the

00:02:52.000 --> 00:02:54.000
internal view of the definition of `foo`.

NOTE Older Emacses

00:02:54.000 --> 00:02:59.000
In older Emacses `o` would be just a

00:02:59.000 --> 00:03:02.000
list that looks... that would look very

00:03:02.000 --> 00:03:05.000
similar to this line here... but in newer

00:03:05.000 --> 00:03:09.000
Emacses the result of this - I mean, the

00:03:09.000 --> 00:03:12.000
the contents of `o` is this thing here,

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that looks quite different

00:03:15.000 --> 00:03:18.000
from this definition.

00:03:18.000 --> 00:03:21.000
So, in older Emacses

00:03:21.000 --> 00:03:25.000
the contents of the

00:03:25.000 --> 00:03:28.000
function cell of `o`...

00:03:28.000 --> 00:03:30.000
sorry, of the function cell of `foo`,

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would be an "old-style lambda",

00:03:32.000 --> 00:03:35.000
that would be just a list like this...

NOTE Newer Emacses

00:03:35.000 --> 00:03:39.000
and in newer Emacses uh the contents of O would

00:03:39.000 --> 00:03:42.000
be a "vector-like lambda"... look for the

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square brackets here - this is a

00:03:44.000 --> 00:03:47.000
vector, but it is preceded by a hash sign.

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So this is what we call

00:03:49.000 --> 00:03:51.000
a "vector-like lambda",

00:03:51.000 --> 00:03:53.000
and vector-like lambas do not

00:03:53.000 --> 00:03:55.000
have a canonical printed representation -

00:03:55.000 --> 00:03:57.000
they have at least two semicanonical

00:03:57.000 --> 00:03:59.000
printed representations...

00:03:59.000 --> 00:04:01.000
The first semicanonical

00:04:01.000 --> 00:04:04.000
printed representation is this one, that is

00:04:04.000 --> 00:04:07.000
generated by a family of functions with

00:04:07.000 --> 00:04:09.000
names like `prin1`...

00:04:09.000 --> 00:04:13.000
and the second semicanonical printed

00:04:13.000 --> 00:04:17.000
representation is like this -

00:04:17.000 --> 00:04:20.000
it looks like a list...

00:04:20.000 --> 00:04:23.000
it looks somewhat like this definition

00:04:23.000 --> 00:04:27.000
of `foo` here, but it has this

00:04:27.000 --> 00:04:29.000
`:dynbind` symbol here...

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and it turns out that when we use

00:04:32.000 --> 00:04:35.000
the `cl-print` family of functions we can

00:04:35.000 --> 00:04:37.000
reconfigure how things are printed...

00:04:37.000 --> 00:04:40.000
and I'm going to show several interesting

00:04:40.000 --> 00:04:47.000
ways of reconfiguring how lambdas are printed,

00:04:47.000 --> 00:04:49.000
and one of the ways is going to

00:04:49.000 --> 00:04:52.000
be like this.

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We can also use the `cl-print`

00:04:56.000 --> 00:04:59.000
functions with my indentation tricks to

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to display how types, or classes, are

00:05:04.000 --> 00:05:07.000
viewed internally by Emacs, and this is a

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big example...

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This is what Emacs considers as being

00:05:14.000 --> 00:05:16.000
the definition of the type

00:05:16.000 --> 00:05:18.000
`cl-structure-class`,

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class and it is this big thing here.

00:05:21.000 --> 00:05:24.000
I edited it very lightly...

00:05:24.000 --> 00:05:30.000
I just deleted some line breaks here.

NOTE Help buttons

00:05:30.000 --> 00:05:33.000
And another thing that I want to

00:05:33.000 --> 00:05:35.000
explain is that Emacs

00:05:35.000 --> 00:05:37.000
has some help functions that

00:05:37.000 --> 00:05:39.000
I have never liked...

00:05:39.000 --> 00:05:41.000
for most people they are good enough,

00:05:41.000 --> 00:05:44.000
but for me they aren't... they...

00:05:44.000 --> 00:05:48.000
uh, well - I'm going to say

00:05:48.000 --> 00:05:50.000
more about this later...

00:05:50.000 --> 00:05:52.000
and, for example,

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if we want a description of what is

00:05:54.000 --> 00:05:58.000
this type here, that we just saw in

00:05:58.000 --> 00:06:00.000
its internal view here...

00:06:00.000 --> 00:06:02.000
we can run either `describe-type`

00:06:02.000 --> 00:06:04.000
or my variant of `describe-type`,

00:06:04.000 --> 00:06:07.000
and we get a help buffer

00:06:07.000 --> 00:06:10.000
that looks like this, in which

00:06:10.000 --> 00:06:13.000
these blue things that are underlined

00:06:13.000 --> 00:06:15.000
are "buttons", in the classical sense...

00:06:15.000 --> 00:06:17.000
you can click on these buttons, or type

00:06:17.000 --> 00:06:19.000
RET on these buttons, and you will be

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taken to another help page, that is

00:06:22.000 --> 00:06:24.000
generated dynamically...

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and you can navigate back and forth...

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and well, whatever...

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and I'm going to explain my

00:06:33.000 --> 00:06:35.000
problems with these kinds of help buffers

00:06:35.000 --> 00:06:37.000
and what I'm trying to do to

00:06:37.000 --> 00:06:41.000
overcome these problems...

NOTE Anyone can learn Lisp in one day

00:06:41.000 --> 00:06:43.000
One of my slogans in this video

00:06:43.000 --> 00:06:44.540
is going to be this one:

00:06:44.541 --> 00:06:46.674
"Anyone can learn Lisp in one day".

00:06:46.675 --> 00:06:50.420
this is a part of a bigger quote

00:06:50.421 --> 00:06:53.040
that I took from a keynote presentation

00:06:53.041 --> 00:06:54.720
by Abelson and Sussman, who

00:06:54.721 --> 00:06:58.000
are two dinosaurs of Computer Science...

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Here is the full quote:

00:07:00.000 --> 00:07:04.000
"Anyone can learn Lisp in one day -

00:07:04.000 --> 00:07:06.000
except that if they already know Fortran

00:07:06.000 --> 00:07:11.000
then it would take three days."

00:07:11.000 --> 00:07:24.000
This is a frame of the video...

00:07:24.000 --> 00:07:28.000
By the way I am going to to add

00:07:28.000 --> 00:07:32.000
this... "and if the person is starting

00:07:32.000 --> 00:07:34.000
with Doom Emacs then it would take 5 years."

00:07:34.000 --> 00:07:39.000
why? I'm going to explain why.

00:07:39.000 --> 00:07:43.000
This is how Emacs used to be.

00:07:43.000 --> 00:07:46.000
If we execute these two expressions here

00:07:46.000 --> 00:07:51.000
the first one... sorry, each symbol can

00:07:51.000 --> 00:07:53.000
have two "values",

00:07:53.000 --> 00:07:54.000
one is its "value as a variable"

00:07:54.000 --> 00:07:58.000
and another one is its "value as a function"...

00:07:58.000 --> 00:08:02.000
and if we run this we store 42

00:08:02.000 --> 00:08:07.000
in the "value cell" of the symbol `foo`, and

00:08:07.000 --> 00:08:11.000
if we run this defun here it stores a

00:08:11.000 --> 00:08:14.000
certain anonymous function in the

00:08:14.000 --> 00:08:18.000
"function cell" of the symbol `foo`...

00:08:18.000 --> 00:08:22.000
and in Emacs, until some time ago

00:08:22.000 --> 00:08:27.000
if we did that and and if we ran

00:08:27.000 --> 00:08:30.774
this expression here the result

00:08:30.775 --> 00:08:32.574
would be 42,

00:08:32.575 --> 00:08:35.000
because of this line here, and if we

00:08:35.000 --> 00:08:37.840
ran this line here the result would be

00:08:37.841 --> 00:08:40.000
the anonymous function corresponding to

00:08:40.000 --> 00:08:41.000
this defun here...

00:08:41.000 --> 00:08:45.000
but now this has changed...

00:08:45.000 --> 00:08:48.000
the result of this thing here is this

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vector-like lambda here - but that doesn't

00:08:51.000 --> 00:08:53.279
matter much now...

00:08:53.280 --> 00:08:57.599
So, until some time ago

00:08:57.600 --> 00:09:00.839
if we did that and if we ran

00:09:00.840 --> 00:09:02.839
this expression here, (foo foo)...

00:09:02.840 --> 00:09:04.599
Emacs would do this: it would

00:09:04.600 --> 00:09:06.000
replace the first `foo` by this

00:09:06.001 --> 00:09:09.000
anonymous function here, it would replace

00:09:09.000 --> 00:09:12.040
the second `foo` by the value of `foo` as a

00:09:12.041 --> 00:09:14.459
variable, that is 42,

00:09:14.460 --> 00:09:16.774
and it would evaluate this, and the

00:09:16.775 --> 00:09:20.000
result would be 420.

00:09:20.000 --> 00:09:23.000
So, again, we used to have this slogan

00:09:23.000 --> 00:09:26.000
here, "anyone can learn Lisp in one day"...

00:09:26.000 --> 00:09:28.000
but now this is gone.

00:09:28.000 --> 00:09:30.000
Let me show... let me talk

00:09:30.000 --> 00:09:34.000
a bit more about why...

NOTE Lambdas for beginners broken

00:09:34.000 --> 00:09:36.000
the title of this slide is

00:09:36.000 --> 00:09:38.000
"Lambdas for beginners broken"...

00:09:38.000 --> 00:09:41.000
if we run this, as I've shown

00:09:41.000 --> 00:09:43.000
in the previous slide...

00:09:43.000 --> 00:09:46.474
in the old style, in old Emacses,

00:09:46.475 --> 00:09:49.279
the result of (symbol-function 'foo)

00:09:49.280 --> 00:09:52.279
would be this anonymous function here...

00:09:52.280 --> 00:09:56.319
and now we get this strange thing here.

00:09:56.320 --> 00:10:00.159
So, this is an "old-style lambda",

00:10:00.160 --> 00:10:03.999
this is a "vector-like lambda",

00:10:04.000 --> 00:10:07.599
and until the middle of 2024

00:10:07.600 --> 00:10:09.399
beginners could learn a lot of Lisp

00:10:09.400 --> 00:10:11.359
by thinking only in terms of

00:10:11.360 --> 00:10:12.960
objects like these...

00:10:13.000 --> 00:10:15.000
this is a function and this

00:10:15.000 --> 00:10:17.000
is an anonymous function, and

00:10:17.000 --> 00:10:20.000
they would learn how to draw cons cell

00:10:20.000 --> 00:10:23.000
diagrams like this thing here and this

00:10:23.000 --> 00:10:25.000
thing here...

00:10:25.000 --> 00:10:26.339
they would think on lists as

00:10:26.340 --> 00:10:29.000
being these trees here, and they

00:10:29.000 --> 00:10:32.000
would be able to understand a lot of

00:10:32.000 --> 00:10:35.000
Lisp just by thinking in these terms...

00:10:35.000 --> 00:10:39.000
and then vector-like lambdas started

00:10:39.000 --> 00:10:43.239
to appear in many places... and if we use

00:10:43.240 --> 00:10:46.474
"vector-like lambdas" in a wide sense,

00:10:46.475 --> 00:10:50.000
to mean all the new objects,

00:10:50.000 --> 00:10:54.000
these new objects, that are

00:10:54.000 --> 00:10:56.000
difficult to visualize... they also started

00:10:56.000 --> 00:10:58.000
to appear in many places.

00:10:58.000 --> 00:11:01.000
This is a continuation of the

00:11:01.000 --> 00:11:04.000
previous slide - this part here is a copy

00:11:04.000 --> 00:11:06.000
of things that were in the previous slide...

00:11:06.000 --> 00:11:12.000
before 2024 beginners could

00:11:12.000 --> 00:11:17.000
open black boxes like this...

00:11:17.000 --> 00:11:20.000
they could try to see what was in the

00:11:20.000 --> 00:11:24.000
function cell of the symbol `foo`...

00:11:24.000 --> 00:11:27.000
and they would see something elegant and

00:11:27.000 --> 00:11:29.000
mind-blowing... and they would start to love

00:11:29.000 --> 00:11:31.000
Lisp immediately.

00:11:31.000 --> 00:11:33.674
Now what they get - what they see -

00:11:33.675 --> 00:11:37.040
is a tiny part of a very complex structure

00:11:37.041 --> 00:11:39.640
that is very powerful but that is

00:11:39.641 --> 00:11:41.000
very difficult to understand...

00:11:41.000 --> 00:11:44.919
and now our beginners are overwhelmed

00:11:44.920 --> 00:11:51.339
instead of mind-blown. Note that I said "black box" here.

00:11:51.340 --> 00:11:53.400
Let me explain the term.

00:11:53.401 --> 00:11:57.539
We can open what's inside of `foo`...

00:11:57.540 --> 00:12:00.140
we can open `foo` to see the contents of

00:12:00.141 --> 00:12:03.007
the symbol `foo`, and we can try to see

00:12:03.008 --> 00:12:06.620
what's in the function cell of the

00:12:06.621 --> 00:12:08.000
symbol `foo`...

00:12:08.000 --> 00:12:10.940
so we can open the box, but what we get

00:12:10.941 --> 00:12:13.000
is something very difficult to understand,

00:12:13.000 --> 00:12:17.000
and so I'm going to say that

00:12:17.000 --> 00:12:21.000
when this happens that box is black.

00:12:21.000 --> 00:12:24.579
It is not totally black - we can open open it -

00:12:24.580 --> 00:12:27.374
but we don't understand what is going on there,

00:12:27.375 --> 00:12:30.000
so we declare that that is black.

00:12:30.000 --> 00:12:36.574
And... when these things started to happen

00:12:36.575 --> 00:12:38.974
_I_ was overwhelmed -

00:12:38.975 --> 00:12:41.974
and in this video I'm going to pretend

00:12:41.975 --> 00:12:44.000
that I was not the only person

00:12:44.000 --> 00:12:47.007
that was overwhelmed

00:12:47.008 --> 00:12:51.240
by these new structures

00:12:51.241 --> 00:12:52.000
that are not so elegant

00:12:52.000 --> 00:12:54.000
as the ones that we had before.

00:12:54.000 --> 00:12:56.000
Anyway...

NOTE Demo

00:12:59.302 --> 00:13:00.599
In the beginning of the video,

00:13:00.600 --> 00:13:02.879
I said that I was going to replace

00:13:02.880 --> 00:13:06.359
the second part of my video from March

00:13:06.360 --> 00:13:08.799
by something that was very easy to test.

00:13:08.800 --> 00:13:11.839
So this is a quick demo for the _very_ impatient.

00:13:11.840 --> 00:13:16.919
I'm recording this in December for the EmacsConf 2025.

00:13:16.920 --> 00:13:18.999
This is the demo that I'm going to present.

00:13:19.000 --> 00:13:21.759
The idea is that people can run the demo a first time

00:13:21.760 --> 00:13:24.399
just to check that everything works

00:13:24.400 --> 00:13:27.559
and to have a notion of how things look like,

00:13:27.560 --> 00:13:29.239
and then, in a second moment,

00:13:29.240 --> 00:13:32.279
they can rerun the demo more slowly

00:13:32.280 --> 00:13:34.879
to understand what each step does.

00:13:34.880 --> 00:13:38.799
So... we are in a file called "00-try-this"...

00:13:38.800 --> 00:13:42.199
and the idea is that we can execute most of this file

00:13:42.200 --> 00:13:45.359
just by typing `f8`​s in the right places.

00:13:45.360 --> 00:13:47.479
Remember that when we type `f8`

00:13:47.480 --> 00:13:49.839
on a line that starts with two red stars,

00:13:49.840 --> 00:13:53.199
eev treats that line as a comment.

00:13:53.200 --> 00:13:58.007
So I'm going to start here... Note that it says in the bottom

00:13:58.008 --> 00:13:59.740
of the screen that this is a comment.

00:13:59.741 --> 00:14:09.879
We are going to run this to download some files...

00:14:09.880 --> 00:14:12.959
Now the files are there...

00:14:12.960 --> 00:14:17.319
This `find-2a` here shows a certain file

00:14:17.320 --> 00:14:19.159
at the window at the right,

00:14:19.160 --> 00:14:22.479
but we don't need to pay attention to that.

00:14:22.480 --> 00:14:24.199
And this thing `load`​s that file.

00:14:24.200 --> 00:14:27.519
So when we load that file, it defines some functions here

00:14:27.520 --> 00:14:29.799
that are going to be used by the rest of the examples.

00:14:29.800 --> 00:14:34.019
Now we can run this thing here... Note that

00:14:34.020 --> 00:14:34.879
we just defined some functions

00:14:34.880 --> 00:14:39.359
and then we ran these functions here... `find-eoutput-2a`...

00:14:39.360 --> 00:14:42.679
and they show some things in the window at the right.

00:14:42.680 --> 00:14:45.679
These things are boring.

00:14:45.680 --> 00:14:49.679
When we run `adt-insert` with argument 42,

00:14:49.680 --> 00:14:52.399
it just shows a 42, in this way...

00:14:52.400 --> 00:14:55.639
The other ones show other numbers... and so on.

00:14:55.640 --> 00:14:59.479
And... what happens when we modify

00:14:59.480 --> 00:15:02.359
this function here, `adt-2`,

00:15:02.360 --> 00:15:05.199
by adding and removing advices to it?

00:15:05.200 --> 00:15:06.919
The idea is that people can run

00:15:06.920 --> 00:15:08.679
this thing here several times,

00:15:08.680 --> 00:15:10.799
watching the window at the right,

00:15:10.800 --> 00:15:14.719
because the results are going to be shown there.

00:15:14.720 --> 00:15:17.799
So, in the first moment, when we run...

00:15:17.800 --> 00:15:21.679
no, no, sorry, sorry, let me run it again.

00:15:21.680 --> 00:15:24.039
In the first moment when we run `adt-2`

00:15:24.040 --> 00:15:28.239
it just shows a 2, and then we modify it in a certain way,

00:15:28.240 --> 00:15:29.479
and we run it again,

00:15:29.480 --> 00:15:33.799
and now before showing the 2 it shows a 1, mysteriously,

00:15:33.800 --> 00:15:37.119
and then we add something to be run after the 2,

00:15:37.120 --> 00:15:38.479
And we run it again,

00:15:38.480 --> 00:15:41.839
and now `adt-2` shows these three things.

00:15:41.840 --> 00:15:43.959
And then we remove the advices,

00:15:43.960 --> 00:15:45.159
we remove these other things,

00:15:45.160 --> 00:15:49.079
and when we run `adt-2` again, it shows only `;; --> 2`.

00:15:49.080 --> 00:15:51.879
It's impossible to understand that in the first time,

00:15:51.880 --> 00:15:57.879
so we can run that several times... to see how things work.

00:15:57.880 --> 00:16:02.279
And now we want to understand

00:16:02.280 --> 00:16:04.959
what changes in the function `adt-2`...

00:16:04.960 --> 00:16:08.639
how it is modified internally.

00:16:08.640 --> 00:16:11.479
I'm calling that the internal view of the function,

00:16:11.480 --> 00:16:13.599
and we are going to compare

00:16:13.600 --> 00:16:16.679
several internal views of the function `adt-2`.

00:16:16.680 --> 00:16:19.999
I'm going to reset the function `adt-2`

00:16:20.000 --> 00:16:25.679
by removing the advices and placing the advices on it again...

00:16:25.680 --> 00:16:28.507
and if we just pretty-print this function here,

00:16:28.508 --> 00:16:36.319
the symbol... the value of this symbol here as a function,

00:16:36.320 --> 00:16:38.639
it is something very ugly.

00:16:38.640 --> 00:16:43.839
But if we print it in another way, with `cl-prin1`,

00:16:43.840 --> 00:16:47.239
then we get something that is much nicer...

00:16:47.240 --> 00:16:51.159
but that is not indented. And if we use this thing here,

00:16:51.160 --> 00:16:55.839
`cl-prin2` instead of `cl-prin1`, it becomes indented.

00:16:55.840 --> 00:17:00.839
So let's try it again.

00:17:00.840 --> 00:17:06.799
Here is the current view of what is `adt-2`.

00:17:06.800 --> 00:17:09.999
So, the original `adt-insert` is here...

00:17:10.000 --> 00:17:11.839
and here are some modifications

00:17:11.840 --> 00:17:13.519
that were added by the advices.

00:17:13.520 --> 00:17:16.759
And we can run these things many times

00:17:16.760 --> 00:17:19.239
to understand what each step does.

00:17:19.240 --> 00:17:21.239
But my suggestion is: in the first time

00:17:21.240 --> 00:17:23.879
just run everything very quickly...

00:17:23.880 --> 00:17:25.199
and then you run it again,

00:17:25.200 --> 00:17:29.119
paying attention to the parts that look more interesting.

NOTE Printing something in different ways for lambdas

00:17:29.120 --> 00:17:37.373
Now, I'm going to... Remember that here

00:17:37.374 --> 00:17:42.559
I printed the contents of `adt-2` in several different ways,

00:17:42.560 --> 00:17:47.119
and now I'm going to show how we can do the same idea

00:17:47.120 --> 00:17:51.599
of printing something in different ways for lambdas...

00:17:51.600 --> 00:17:52.919
that is something that I explained

00:17:52.920 --> 00:17:54.639
in the first part of the video.

00:17:54.640 --> 00:18:00.639
In this part of the demo we define a function `foo`...

00:18:00.640 --> 00:18:06.360
this `setq` here defines `o` as

00:18:06.361 --> 00:18:08.959
the contents of the function cell of `foo`...

00:18:08.960 --> 00:18:12.999
And now we are going to print

00:18:13.000 --> 00:18:15.399
that `o` in several different ways.

00:18:15.400 --> 00:18:19.199
The default way is this one, it's very ugly,

00:18:19.200 --> 00:18:22.239
but we can redefine how these things are printed

00:18:22.240 --> 00:18:24.559
by just running these lines...

00:18:24.560 --> 00:18:28.719
and if we pay attention at what's happening

00:18:28.720 --> 00:18:30.519
at the window at the right,

00:18:30.520 --> 00:18:33.559
we can see that we have several different

00:18:33.560 --> 00:18:35.759
printed representations for the same thing...

00:18:35.760 --> 00:18:36.879
and then at the last step,

00:18:36.880 --> 00:18:41.079
we reset the printer to the default representation.

00:18:41.080 --> 00:18:43.279
And the details are here.

00:18:43.280 --> 00:18:44.999
If we run these lines here,

00:18:45.000 --> 00:18:48.759
they show the definitions at the window at the right.

00:18:48.760 --> 00:18:53.879
And this... now comes the difficult part,

00:18:53.880 --> 00:18:56.679
in which we have to do something

00:18:56.680 --> 00:19:02.079
besides just running things with F8. We need

00:19:02.080 --> 00:19:04.919
a help buffer with buttons...

00:19:04.920 --> 00:19:08.919
buttons in the traditional sense,

00:19:08.920 --> 00:19:11.559
and we need to choose a certain button there,

00:19:11.560 --> 00:19:13.439
or any button there,

00:19:13.440 --> 00:19:17.940
and run `M-x ee-set-button` on that button.

00:19:17.941 --> 00:19:24.719
So, let me define a `struct` here,

00:19:24.720 --> 00:19:29.359
and this is some help on what is that structure.

00:19:29.360 --> 00:19:33.599
I'm going to choose this button here

00:19:33.600 --> 00:19:40.159
and I'm going to type `M-x ee-set-button`.

00:19:40.160 --> 00:19:43.559
The message is a bit obscure.

00:19:43.560 --> 00:19:47.959
And now we have something that displays

00:19:47.960 --> 00:19:51.079
a lot of information about that button...

00:19:51.080 --> 00:19:53.919
And we can also run that with just `F8`s.

00:19:53.920 --> 00:20:00.279
By the way, if we want to understand

00:20:00.280 --> 00:20:02.319
the code that's behind these things,

00:20:02.320 --> 00:20:04.839
we can run this sexp here.

00:20:04.840 --> 00:20:07.219
It is going to show the code here at the right.

00:20:07.220 --> 00:20:10.759
But anyway, these first lines here...

00:20:10.760 --> 00:20:15.479
they display the output in the echo area... Let's try...

00:20:15.480 --> 00:20:20.559
And each one of them extracts a different part

00:20:20.560 --> 00:20:22.559
of the information on that button.

00:20:22.560 --> 00:20:26.039
And these other lines here create a three-window setting

00:20:26.040 --> 00:20:29.639
in which the help buffer is shown here,

00:20:29.640 --> 00:20:33.119
and the result of some other thing

00:20:33.120 --> 00:20:39.979
is shown in the third window. Let's try...

00:20:39.980 --> 00:20:46.107
So now that we have... well... I said

00:20:46.108 --> 00:20:48.407
that we needed to choose a certain button

00:20:48.408 --> 00:20:53.439
and run `M-x ee-set-button` there. We have done that...

00:20:53.440 --> 00:20:55.919
so now this variable `ee-button`

00:20:55.920 --> 00:20:58.439
contains information about the button...

00:20:58.440 --> 00:21:01.119
And now we can run this part here

00:21:01.120 --> 00:21:03.479
as many times as we want to...

00:21:03.480 --> 00:21:07.479
try to understand what are the values of these things here...

00:21:07.480 --> 00:21:11.679
and how some things start with a value that is very complex

00:21:11.680 --> 00:21:13.839
and very difficult to understand,

00:21:13.840 --> 00:21:16.839
and then we extract the more interesting parts.

00:21:16.840 --> 00:21:22.279
And the details, as I said, are here.

00:21:22.280 --> 00:21:26.759
That was the end of the demo, and my question is,

00:21:26.760 --> 00:21:28.559
what was your reaction to that?

00:21:28.560 --> 00:21:32.679
If your reaction was more like "wow" than like "blergh"

00:21:32.680 --> 00:21:37.039
then you might like the last part of the video that I recorded in March,

00:21:37.040 --> 00:21:38.399
that was very technical...

00:21:38.400 --> 00:21:42.719
When I recorded it, I thought, oh my god, this video is very bad...

00:21:42.720 --> 00:21:47.279
only the hardcore eev users are going to like that,

00:21:47.280 --> 00:21:51.039
and there are less than five hardcore

00:21:51.040 --> 00:21:52.839
eev users in the world...

NOTE Exploring buttons

00:21:52.840 --> 00:21:56.639
But anyway, if you saw that introduction

00:21:56.640 --> 00:21:59.079
and you think that these things are interesting,

00:21:59.080 --> 00:22:02.999
you can execute any one of these S-expressions here

00:22:03.000 --> 00:22:05.999
and take a look at the final part of that video

00:22:06.000 --> 00:22:09.559
that describes how I wrote some functions

00:22:09.560 --> 00:22:14.239
for exploring buttons. If you execute this sexp here,

00:22:14.240 --> 00:22:19.559
it plays a part of the video starting from that position.

00:22:19.560 --> 00:22:26.919
If you execute this one, you go to the subtitles in HTML...

00:22:26.920 --> 00:22:30.559
and if you run this one, you go

00:22:30.560 --> 00:22:36.159
to the subtitles in another format. And... that's it!

00:22:36.160 --> 00:22:40.119
No, no, sorry, I said "that's it",

00:22:40.120 --> 00:22:42.159
but I forgot a very important part...

NOTE Some design decisions behind eev

00:22:42.160 --> 00:22:45.159
I had prepared this slide here

00:22:45.160 --> 00:22:48.507
to explain some design decisions behind eev

00:22:48.508 --> 00:22:53.679
and why there are so few users of eev... and let me do that.

00:22:53.680 --> 00:22:57.919
The thing is that my working memory is very small,

00:22:57.920 --> 00:23:01.279
and I need examples that are easy to visualize...

00:23:01.280 --> 00:23:04.959
ideally, examples that are easy to run

00:23:04.960 --> 00:23:10.307
and that I can compare the outputs

00:23:10.308 --> 00:23:12.159
of different ways of running them.

00:23:12.160 --> 00:23:16.359
For me, understanding specifications

00:23:16.360 --> 00:23:20.679
in an API is not enough... examples work much better for me.

00:23:20.680 --> 00:23:24.439
Also, I make lots of mistakes when I type...

00:23:24.440 --> 00:23:28.399
so I need ways to run my executable notes

00:23:28.400 --> 00:23:31.879
by just typing `f8` and `M-e`...

00:23:31.880 --> 00:23:37.039
and... most people in the #emacs channel and in other places

00:23:37.040 --> 00:23:44.519
recommend executing sexps by typing `M-:`, like this...

00:23:44.520 --> 00:23:49.239
But I hate that... I think that `M-:` and IELM are

00:23:49.240 --> 00:23:54.559
for people who type well, so not me...

00:23:54.560 --> 00:23:58.839
And also, 99% of what I do is scratch code.

00:23:58.840 --> 00:24:01.639
Very few things that I do go

00:24:01.640 --> 00:24:05.799
into "production" - between quotes.

NOTE Tests

00:24:05.800 --> 00:24:10.199
So most of my tests are not automated tests.

00:24:10.200 --> 00:24:12.439
They are just things that I run with F8,

00:24:12.440 --> 00:24:15.879
and they don't include the expected result.

00:24:15.880 --> 00:24:19.159
Many people feel that this is very, very, very wrong.

00:24:19.160 --> 00:24:23.279
Tests MUST MEAN automated tests.

00:24:23.280 --> 00:24:25.639
Also, and this is very frustrating,

00:24:25.640 --> 00:24:28.399
eev has lots of "non-users",

00:24:28.400 --> 00:24:31.519
I mean, people who have tried to use it,

00:24:31.520 --> 00:24:34.759
but they said that they couldn't figure out how to use it.

00:24:34.760 --> 00:24:36.159
They couldn't understand

00:24:36.160 --> 00:24:38.079
what would be the workflows for eev.

00:24:38.080 --> 00:24:43.679
And that's the same that happens with me with code blocks in Org...

00:24:43.680 --> 00:24:48.759
I'm still at the point in which code blocks in Org just feel wrong.

00:24:48.760 --> 00:24:55.199
I still don't understand how to organize my workflows around code blocks.

00:24:55.200 --> 00:24:58.999
I said that eev has very few users,

00:24:59.000 --> 00:25:02.239
and they are all very weird and very busy,

00:25:02.240 --> 00:25:06.359
and I decided that all my blog-ish posts about eev

00:25:06.360 --> 00:25:09.719
would be things that they can run in a few minutes...

00:25:09.720 --> 00:25:13.039
just like the demo that I showed a few minutes ago.

00:25:13.040 --> 00:25:16.119
I said "like the examples in the rest of the video",

00:25:16.120 --> 00:25:17.399
but I forgot this slide,

00:25:17.400 --> 00:25:19.639
and I'm recording this after the demo.

00:25:19.640 --> 00:25:22.520
So... that's it. Thanks!