Irreal

Over at the Emacs Elements Channel there’s another useful video up. This time it’s about the Emacs Help system. The majority of experienced Emacs users will already be familiar with most of the material but if you’re a learn-as-you-go user, there may be some information new to you.

The first thing is that Ctrl+h Ctrl+h will show you a list of all the help commands. If you’re like me, you know this but always forget it when you’re trying to remember a help command. There are a lot more commands then the ones you use everyday so it’s worth your while to type Ctrl+h Ctrl+h to see what’s available.

For example, I’d completely forgotten about Ctrl+H w to discover the shortcut for a given command. My usual procedure is to bring up the documentation for the command and get the information there but I’m going to try to remember to use Ctrl+h w instead.

Another thing that I learned from the video is the difference between scrolling up and down with Space and Delete versus the <PgUp> and <PgDn> keys. I’ll let you watch the video to see what that difference is.

The video is 14 minutes 52 seconds long so it shouldn’t be too hard to find time but you may have to plan ahead.

I’ve written about Clojure’s threading macros and their implementation in Elisp before [1, 2, 3, 4, 5]. I like them but almost always use the traditional composition of functions instead. That’s probably because being a mathematician it seems natural to me. Still, the threading macros are easier to read and understand.

Most people who care about such things know about Magnar Sveen’s implementation of these macros in his Dash library. They have the advantage of using the same names, ->, ->>, etc. as clojure. Of course, you have to install Dash to use them. That’s not much of a problem because so many packages use Dash that it’s probably already installed.

But what if you don’t want the dependency? It turns out that Elisp has the most important of these macros built in and has since at least Emacs 25. The first, thread-first corresponds to -> and the second, thread-last, corresponds to ->>. They live in the sub-x.el file if you want to check out there definition.

Ruslan Bekenev has a page that explains all this and even gives a short explanation of how to use the macros. If you’re interested in the threading macros, take a look at his post.

The other day I wrote about installing elfeed-webkit to render my RSS feed as proper HTML. I was pretty impressed with it when I first tried it and now I’m even more of a fan. Before elfeed-webkit, I spent a lot of time switching between Elfeed and Safari so that I could read interesting posts that came up in the feed. It doesn’t seem like it would take that much time but since the change, my RSS workflow seems faster and easier.

A secondary advantage is that Emacs has more functionality now that I have XWidgets enabled. At first I wondered if I could get eww to do a better job rendering sites by using Webkit. That turned out to be a bust but I did discover xwidget-webkit-broswse-url that will render a site in decent HTML but it’s not a proper Browser so it’s pretty much restricted to viewing a specific URL. You can follow links and control videos but there are no bookmarks, content filtering, or other Browser amenities. Still, it does help keep me in Emacs and a lot of times I just want to visit a page from Emacs and it works perfectly for that.

In my original post, I noted a couple of problems. The first was the possibility of being inundated with ads because of the lack of content filtering. That’s basically a nonissue for the sites I read although occasionally a feed item will send me off to a “commercial” site that does have a lot of intrusive pop-up adds but it doesn’t happen often.

The second problem was that I couldn’t get t to toggle elfeed-webkit on and off. I thought maybe something else was grabbing the t binding to I changed it to w but that didn’t work either. I solved that by binding a global key to toggle elfeed-webkit and that worked fine (but see below).

Finally, I recently upgraded my email client mu/mu4e and a helper function I wrote to display the post in eww stopped working. While investigating that, I discovered that mu4e will display an email with webkit, which is what I really want so I’m now using that instead of eww.

While investigating the email issue I discovered that the XWidget library does indeed capture the t key as well as the w key. The t doesn’t appear to do anything useful as its definition

(define-key map "t" (lambda () (interactive) (message "o"))) ;FIXME: ?!?

shows. I don’t know how it was working for Grabo; perhaps he’s using the Emacs 29 pretest and it has removed the useless binding. In any event, I simple changed my toggle key to x and now it works perfectly.

That leaves only one small problem. One of the sites I follow, Daring Fireball, has the unusual property that its RSS URL is not the site itself but the site it’s linking to. That means that I miss the Daring Fireball commentary and go straight to the linked site. I’m considering adding code to implement a tag that inhibits rather than enables elfeed-webkit. In the meantime, I’m simply toggling elfeed-webkit off when I get to a Daring Fireball post.

All in all, I’m really happy with elfeed-webkit and recommend it wholeheartedly.

I just stumbled across a post by Fritz Grabo about his package elfeed-webkit. When I first saw it, I thought it was interesting and worth a look. After reading more about it, I knew I had to install it. That wasn’t entirely easy because I had to recompile my Emacs to support xwidgets. But I liked the idea of the package enough to press on and add xwidgets to my Emacs.

After that, it was simply a matter of installing elfeed-webkit from MELPA. When I toggled it on with Meta+x elfeed-webkit-toggle all my elfeed results were rendered directly in the Elfeed buffer. Sometimes—for example, when I want to save a page for an Irreal post—I need to go to the browser and rerender the page. That’s simply done by pressing the v key.

You’re supposed to be able to toggle elfeed-webkit on and off with a t after you configure it in your init.el but I can only get it to toggle on, not off. Doubtless, I have some misconfiguration but that’s research for another day. You can also add a tag to individual feeds to turn it on but I haven’t tested that yet (I installed it just before I started this post).

So far, I really like this package. It (mostly) keeps me in Emacs and renders the pages perfectly. A comment in the original reddit post complained that Webkit was going to deluge my feeds with dozens of ads but I didn’t notice that with my admittedly limited testing. The nice thing is that you’re not really committed. It’s easy to turn it off or even uninstall it if you don’t like it. The worst that happens is that you end up with support of xwidgets in your Emacs.

As far as I know, it started with this reddit post. It was a request for a “built with Emacs” badge. Those badges were the type of thing you used to see on Web sites. I’m pretty sure I had it on one of my old Web sites¹ but I don’t see them as much now. In any event, MichalNemecek had seen one for Vim and wanted to put it on his site. The problem was that he’d switched to Emacs and was looking for something similar for Emacs users.

Since then, I’ve seen several mentions of this page from Lulu Cathrinus Grimalkin that has a collection of Emacs badges. It even has the famous—or is it infamous—kitchen sink Emacs badge. If you’re into this sort of thing and would like to add an Emacs badge to your site, Grimalkin’s page is a handy reference.

I’m guessing that the reason you don’t see these very much anymore is that blogs and sites are mostly no longer handmade but use something like WordPress, Hugo, or one of the other site generators. That and the fact blogs are no longer the exclusive domain of nerds. These days, the average blogger has probably never heard of Emacs or Vim.

In any event, if you want one of those badges, now you know were to find it.

Over at Emacs Elements there’s a nice video that explores Emacs regular expressions. One the one hand, virtually everyone hates Emacs regular expressions and wishes that Emacs used Perl compatible regexes instead. On the other hand, a case can be made that Emacs regexes are optimized for the typical Emacs use cases. In either case, it’s an old war and a boring one. One can arrange to use Perl regexes but most of us just accept the pain and use the default.

Still, even for those of us who have accepted the inevitable, the rules governing Emacs regexes can seem arcane and sometimes needlessly complex. Why, for example, do we have to use [0-9] instead of \d to specify a digit?

Emacs Elements’ latest video is a nice précis of the rules and conventions for using regexes in Emacs. The three parts that I really liked were

1. Listing the exact characters that need to be escaped
2. A good explanation of how to search using syntax classes
3. An explanation of the non-greedy operators

but the video covered most aspects Emacs regular expressions and is a good explanation or refresher for those who have occasion to use them. The video is 22 and a quarter minutes so you’ll probably have to schedule some time but it’s definitely worth watching.