As any Common Lisp coder knows, a REPL is an incredibly useful tool. It can be used not just for development, but for running all sorts of tasks. Personally, I don't bother making my Lisp tools into executable scripts and just run them directly from SLIME. As such, any operation that requires leaving the REPL is quite inconvenient. For me, one such operation was viewing image files, for example in conjunction with my match-client:match tool. So lately I've been researching various methods to incorporate this functionality into the normal REPL workflow. Below, I present 3 methods that can be used to achieve this.

Open in external program

This one's easy. When you want to view a file, launch an external process with your favorite image viewer. On Windows a shell command consisting of the image filename would launch the associated application, on Linux it's necessary to provide the name of the image viewer.

(defvar *image-app* nil) ;; set it to '("eog") or something

(defun view-file-native (file)
  (let ((ns (uiop:native-namestring file)))
    (uiop:launch-program (if *image-app*
                             (append *image-app* (list ns))
                             (uiop:escape-shell-token ns)))))

Note that uiop:launch-program is used instead of uiop:run-program. The difference is that launch- is non-blocking - you can continue to work in your REPL while the image is displayed, whereas run- will not return until you close the image viewer.

Also note that when the first argument to run/launch-program is a string, it is not escaped, so I have to do it manually. And if the first argument is a list, it must be a program and a list of its arguments, so merely using (list ns) wouldn’t work on Windows.

Inline image in REPL

The disadvantage of the previous method is that the external program might steal focus, appear on top of your REPL and disrupt your workflow. And it's well known that Emacs can do everything, including viewing images, so why not use that?

In fact, SLIME has a plugin specifically for displaying images in REPL, slime-media. However it’s difficult to find any information on how to use it. Eventually I figured out that SWANK (SLIME’s CL backend) needs to send an event :write-image with appropriate arguments and slime-media's handler will display it right in the REPL. The easiest way is to just send the file path. The second argument is the resulting image's string value. If you copy-paste (sorry, "kill-yank") it in the repl, it would act just like if you typed this string.

(swank::send-to-emacs '(:write-image "/path/to/test.png" "test"))

You can even send raw image data using this method. I don't have anything on hand to generate raw image data so here's some code that reads from a file, converts it to a base64 string and sends it over SWANK.

(with-open-file (in "/path/to/test.png" :direction :input  :element-type '(unsigned-byte 8))
                (let* ((arr (make-array (file-length in) :element-type '(unsigned-byte 8)))
                       (b64 (progn (read-sequence arr in) (cl-base64:usb8-array-to-base64-string arr))))
                  (swank::send-to-emacs `(:write-image ((:data ,b64 :type swank-io-package::png)) "12345"))))

Note that the first argument to :write-image must be a list with a single element, which is itself a plist containing :data and :type keys. :data must be a base64-encoded raw image data. :type must be a symbol in swank-io-package. It’s not exactly convenient, so if you’re going to use this functionality a helper function/macro might be necessary.

Image in a SLIME popup buffer

Inline images are not always convenient. They can’t be resized, and will take up as much space as is necessary to display them. Meanwhile EMACS itself has a built-in image viewer (image-mode) which can fit images to width or height of a buffer. And SLIME has a concept of a “popup buffer” which is for example used by macroexpander (C-c C-m) to display the result of a macro expansion in a separate window.

Interestingly, slime-media.el defines an event :popup-buffer but it seems impossible to trigger it from SWANK. It is however a useful code reference for how to create the popup buffer in ELisp. This time we won’t bother with “events” and just straight up execute some ELisp code using swank::eval-in-emacs. However by default, this feature is disabled on Emacs-side, so you’ll have to set Emacs variable slime-enable-evaluate-in-emacs to t in order for this method to work.

Also Emacs must be compiled with ImageMagick for the resizing functionality to work.

Anyway, the code to view file in the popup buffer looks like this:

(defun view-file-slime (file &key (bufname "*image-viewer*"))
  (let ((ns (namestring file)))
    (swank::eval-in-emacs
     `(progn
        (slime-with-popup-buffer (,bufname :connection t :package t)
          (insert-image (create-image ,ns))
          (image-mode)
          (setf buffer-file-name ,ns)
          (not-modified)
          (image-toggle-display-image))
        ;; try to resize the image after the buffer is displayed
        (with-current-buffer ,bufname (image-toggle-display-image))))))
    ))

Arriving to this solution has required reading image-mode’s source code to understand what exactly makes image-mode behave just like if the image file was opened in Emacs via C-x C-f. First off, image-mode can be a major and a minor mode - and the minor mode is not nearly as useful. slime-with-popup-buffer has a :mode keyword argument but it would cause image-mode to be set before the image is inserted, and it will be a minor mode in this case! Therefore (image-mode) must be called after insert-image.

Next, the buffer must satisfy several conditions in order to get image data from the filename and not from the buffer itself. Technically it shouldn’t be necessary, but I couldn’t get auto resizing to work when data-p is true. So I set buffer-file-name to image’s filename and set not-modified flag on.

Next, image-toggle-display-image is called to possibly resize the image according to image-mode settings. It's called outside of slime-with-popup-buffer for the following reason: the buffer might not yet be visible and have any specific dimensions assigned to it, and therefore resizing will do nothing.

Here’s an example of how calling this function looks in Emacs.

The position of the popup buffer depends on whether the original Emacs window is wide enough or not. I think it looks better when it’s divided vertically. Use M-x image-transform-fit-to-height or M-x image-transform-fit-to-width to set up the auto-resizing method (it gets remembered for future images). Unfortunately there’s no way to fit both height and width, at least with vanilla Emacs. I prefer fit-to-width because in case the image is too tall, it is possible to scroll the image vertically with M-PgDn and M-PgUp from the other buffer. Unlike other image-mode buffers, this buffer supports a shortcut q to close itself, as well as various SLIME shortcuts, for example C-c C-z to return to the REPL.

That's it for now, hope you enjoyed this overview and if you happen to know a better way to display images in Emacs, I would be interested to hear about it.

It's a new month, and that usually means I'm supposed to write a monthly update on the progress with Kandria. Thinking about that though made me feel very depressed because I realised that I hadn't really done anything at all for the game, all of April.

I can blame however much I want of that on the quarantine and university stress, or whatever else, but it won't change the fact that there has not been much progress on any front. While I have been slacking a lot, it's not like I haven't been working at all - plenty of time has gone into Courier, after all.

When I had this realisation yesterday, I tried my best to push myself to work on the game any way I could, but I failed to find anything that I could actually convince myself to do. That isn't to say that there aren't things to do; god forbid there's a tonne of things! Tuning combat, drawing animations, writing the UI, fixing dialogue, starting on enemy AI, optimising performance - just to name a few. And yet, despite the breadth and depth of things to do, there was absolutely nothing that looked appealing to me.

This kind of feeling is nothing new to me. It's a creative block, and happens more often that I'd like to admit. It's also why I often don't like to start long running projects, because I'm afraid of a creative block that would ruin it. The worst part about the creative block is that there's no remedy for it. You just get stuck in a rut, and it sucks a whole lot for a completely unpredictable amount of time. Often what I end up doing, whether consciously so or not, is switching to another project and just working on that.

So far that project has been Courier, but that's at its end and I'm also starting to feel burnt out on it, too. I don't have any other projects queued up that I'd like to tackle, or new ideas on what to do at the moment, so I'm just... stuck.

I suppose the right thing to do in this situation is to take it easy and not fret too much over it, since that's often one of the many factors causing the block. I've never been good at actually doing that, though. Maybe I should try to take a break from programming in general? I don't know.

You may be wondering why I'm writing this all to begin with. Well, partly I feel like I promised to do monthly and weekly updates, and I really hate to break that promise without notice. Another part is that I just feel like I owe you the discretion to tell you what's going on with me. I'm very thankful for the email replies and general responses I've gotten for Kandria so far, I really am! Because of that genuine interest, I feel all the more pressured not to disappoint. Since I have nothing to show though, I thought the only proper course of action is to just be open and direct about it. So I'll just say it again: aside from updating the public demo, no progress has been made at all.

Maybe it would help me to have a more open discussion about this topic in general, instead of just it being me telling you that I'm in a bad place. So please, let me know: have you been in similar situations before? What helped you deal with them? Is there something in Kandria I could try to focus on that you, personally, would like to see?

You can reach me at shinmera@tymoon.eu.

I have finally obtained the first batch of the printed "Programming Algorithms" books and will shortly be sending them to the 13 people who asked for a hardcopy.

Here is a short video showing the book "in action":

If you also want to get a copy, here's how you do it:

1. Send the money to my PayPal account: $30 if you want normal shipping or $35 if you want a tracking number. (The details on shipping are below).
2. Shoot me an email to vseloved@gmail.com with your postal address.
3. Once I see the donation, I'll go to the post office and send you the book.
4. Optionaly step: if you want it to be signed, please, indicate it in your letter.

Shipping details: As I said originally, the price of the dead-tree version will be $20+shipping. I'll ship via the Ukrainian national post. You can do the fee calculation online here (book weight is 0.58 kg, size is 23 x 17 x 2 cm): https://calc.ukrposhta.ua/international-calculator. Alas, the interface is only in Ukrainian. According to the examples I've tried, the cost will be approximately $10-15. To make it easier, I've just settled on $10 shipping without a tracking number of $15 if you want a tracking number. Regardless of your country. I don't know how long it will take - probably depends on the location (I'll try to inquire when sending).

The book was already downloaded more than 1170 times (I'm not putting the exact number here as it's constantly growing little by little). I wish I knew how many people have, actually, read it in full or in part. I've also received some error corrections (special thanks goes to Serge Kruk), several small reviews and letters of encouragement. Those were very valuable and I hope to see more :)

Greetings from the far away city of Lima, Peru!
I loved this part: "Only losers don't comment their code, and comments will be used extensively"
Thank you so much for putting this comprehensive collection of highly important data structures, i'm already recommending this to two of my developers, which I hope i'll induce into my Lisp addiction.
--Flavio Egoavil

And here's another one:

Massively impressive book you've written! I've been a Lisp programmer for a long time and truly appreciate the work put in here. Making Lisp accessible for more people in relation to practical algorithms is very hard to do. But you truly made it. You'll definitely end up in the gallery of great and modern Lisp contributions like "Land of Lisp" and "Let Over Lambda". Totally agree with your path to focus on practical algorithmic thinking with Lisp and not messing it up with macros, oop and other advanced concepts.
--Lars Hård

Thanks guys, it's really appreciated!

If you feel the same or you've liked the book in some respect and have found it useful, please, continue to share news about it: that definitely helps attract more readers. And my main goal is to make it as widely read as possible...

So, I ordered a bunch of native plants on Etsy, and they were WAY cheaper than they are in stores around here. They came as chunks of root, essentially. It only occurred to me after I ordered to worry about why they were so cheap — is it possible they’re being illegally harvested from woodlands? … Continue reading "Native Plants From Etsy"

Jack-in-the-pulpit, another native with a great name.  And such an unusual appearance. The roots are apparently edible, but only with some serious treatment — you have to let them dry for at least six months, then roast them, then grind them to mix in with flour…otherwise, you can get severe irritation of the mouth. I’m having … Continue reading "Jack-in-the-pulpit"

Anyone know what this lovely tree is? Spotted in Mills Park.

Heh. K Tempest Bradford happened across an old photo of me and Neil — I’m in a sari, so I’m guessing this was at the Hugos. We look very young, so at least a decade ago — maybe two. 

Packed up the first of the local Mother’s Day treat packages — lily-of-the-valley soap and bath salts, baked goodies and confections. And locals get a little potted lily-of-the-valley too. Supplies limited — I think I can do 4 more before I run out of cookies. I’m done with baking for a bit…need to get back … Continue reading "There Will Be Dragons"

I had a small dip in productivity this week. I think I mentioned that at the end of last summer I had shingles. It was a super mild case, but I wound up with something called “post-herpetic neuralgia” which is basically nerve pain. It’s super well-controlled with gabapentin, which also has some positive effects on […]

So hey I think I managed to break a leisure record this Virgo Month of Leisure! The bad news is that’s because I’ve been feeling borderline punk for a few months now. I always thought of myself as someone in pretty good shape, but every so often I just come down with… sinus nonsense, or […]

I went to Florida a few weeks back which will be the last time I get on a plane this year unless something wacky happens. Thinking more about carbon footprint stuff even though I am doing solidly well in that regard because I have no kids. It was a good time, pictures are here. I […]

As I was driving back from Kate’s house after a three-day Thanksgiving trip (as opposed to a nine-day one which is my usual MO) I was thinking of a list I’d put here. Whether I’m online or off, I’m usually thinking of lists. To do lists, reading lists, library lists, “crap to fix in my […]

Really serious about staying out of airplanes now. Two airplane trips this year. A low key summer not feeling terrific. Lots of time doing more local stuff and not regretting it at all. Here is the short list of places. Four states. Stars indicate multiple visits to the exact same place. Past years: 2018, 2017, […]

January is a hunkering month. I get out when I can, stay home when I can’t, keep the sun box pointed at my face, and work on Wikipedia, learning new things and giving other people the chance to learn about my world. The #Lib1Ref campaign is happening, I’m barely paying attention to it, but it’s as […]

So I’d been kind of waiting until I had a positive “Hey I’m feeling better!” update. I had my head down, doing my thing, being basically okay but a little crabby at having felt kinda lousy since August. And two things happened. 1. COVID-19 2. The medicine my doc gave me for GERD (or something […]

So except for a single slice of pizza, I haven’t eaten anything I didn’t make at home for a month. I’m a decent cook and have a decent pantry. But more to the point, I have a huge tolerance for eating the same thing over and over again. This means batch cooking, even for one, […]

Все знают, коллектив MusicAeterna и его художественный руководитель Теодор Курентзис с декабря 2019 года активно работают над проектом культурно-образовательного центра Р. А. Д. И. О. в Санкт-Петербургском Доме Радио. Но карантин вносит в эту работу свои коррективы, и в конце апреля было объявлено об открытии digital platform — виртуальной творческой резиденции MusicAeterna. В скором времени на ней будет доступна онлайн-версия перформанса Алексея Ретинского «Слышать», посвященный Людвигу ван Бетховену. Анонсируем это событие статьей Анны Самсоненко, побывавшей на единственном представлении в феврале.

So Martin Scorsese said that the Marvel movies are “not cinema” and the internet kind of blew up because it is inherently polarizing, and the possibility that Scorsese is both one of our most talented living directors and also wrong about this particular subject is not particularly fun discourse for a lot of people on […]

This is the Call for Nominations for the 2019 Theszie Awards (the rec.sport.pro-wrestling Awards). To nominate candidates for all categories, you may use this form. Nominations are due by January 5, 2019. Finally, to see previous years’ results, click here for 2018, click here for 2017, here for 2016, here for 2015, here for 2014, […]

This is the Call for Votes for the 2019 RSPW (Theszie) Awards. You can vote here. The Theszies are the oldest fan awards in pro wrestling history, going back to 1990 (when Mr. Perfect quite appropriately won Best Wrestler and Junkyard Dog v. Ric Flair at Clash of the Champions XI won Worst Match). They […]

Welcome to the results of the 2019 Theszies / Rec.sport.pro-wrestling Awards. (Editor’s note: Some of you may be wondering “what took so long?” The answer is: 1.) Immediately after the voting period ended, my wife and I went on a previously-scheduled vacation to Italy, which was great, and 2.) then when we got back we […]