Irreal

Jon Eskin has a revealing post that shows how easy it is to use the Elisp debugger. The debugger, Edebug, is documented in the Emacs Lisp manual so of course it’s always available in your Emacs session.

What I liked about the post was that it shows how easy it is to use Edebug to solve a problem even if you don’t really know the code base. Usually when you think about a debugger, there’s a supposition that it will be complex, hard to use, and have lots of mysterious commands. Eskin’s post shows otherwise.

The entire debugging session involved two commands. First, the suspect function is intrumented with Ctrl+u Meta+Ctrl+x so that Eskin could step through the function and see what it was doing. It turned out that a variable was being unexpectedly changed. To track down the culprit, Eskin put a watchpoint on the variable and was able to see exactly what was changing it. After that, the problem and its fix was obvious.

There’s more to Edebug, of course, but it’s amazing how far you can get with just the two commands that Eskin used. Notice that Eskin wasn’t writing Elisp code, he merely wanted to track down a problem in existing code. That shows that Edebug can be useful to many different types of users. If you aren’t already familiar with Edebug, take a look at Eskin’s post and then read over the Edebug chapter in the Elisp manual.

Stefan Kangas just announced that use-package has been merged into the emacs-29 branch. I’m inclined to take a conservative view towards moving packages into core Emacs, believing that a package should prove its worth and stability over an extended time before being considered for core.

The use-package macro has clearly met that standard. It really does make configuring packages simpler and the size of the configuration files smaller. Like many of our most useful tools, use-package was intended to make things a bit easier for its author, John Wiegley. He put it on GitHub and soon many people were using it and offering extensions. The :ensure keyword, for example, was implemented by one those users. Wiegley himself doesn’t use it because his workflow is a bit different.

The use-package package is a small thing but it does make my life simpler and I’m glad to see it get merged into core. Thanks to Wiegley, Kangas, and the others who made this happen.

As most Irreal readers know, Protesilaos Stavrou (Prot) is looking for a new job. Part of his preparations is learning Clojure so of course he’s produced a video on using Clojure in Emacs with Clojure. It’s an elementary exposition but definitely worth watching.

The main point of the video is not Clojure itself but rather the use of Cider and the evaluation of expressions in the context of the code buffer. He shows how you can evaluate an expression from within the code buffer and how you can easily switch to the Clojure REPL to try things out.

It’s another example of exploratory programming that I’ve written about before. If you haven’t experienced it, it’s hard to overstate the value of having the REPL always available to test out functions or even expressions. It makes programming much more efficient and fun.

The video is just short of 27 minutes so you’ll have to schedule some time. Prot has promised more videos on Clojure, which I’m looking forward to. In the mean time, if you want to get a sense of what using Cider is like, take a look at his video. If you want another example, check out Mike Zamansky’s video on Day 1 and 2 of the 2022 Advent of Code challenge. He uses Clojure and demonstrates its use on nontrivial problems.

Regular Irreal readers know that I’m a fan of Howard Abrams’ posts and videos on Emacs. Abrams gave a talk at EmacsConf 2022 on the Top 10 reasons why you should be using Eshell. He felt that the talk was a little compressed so he wrote a separate blog post that covers the same material.

I found that the best strategy is to listen to the talk and then read the post to fill in any details that you might have missed in the video. The video ran to 14 minutes so it should be easy to find time for it.

Like much useful software, Eshell is pretty easy for trivial operations but also has powerful, advanced features that are very useful but harder to learn. The canonical example of this is file glob filters. They’re also available in Zshell and I’m always promising myself to learn them but unless I use them all the time I tend to forget the details.

Abrams also demonstrates some of his bespoke code that he uses to make using Eshell easier. For applications that require things like cursor addressing, he uses vterm but for most things he prefers Eshell. The nice thing, he says, is that Eshell is both a shell and an Elisp REPL at the same time. Again, the syntax is a bit different from Bash or Zshell so you need to use it regularly to internalize it.

Spend 14 minutes with the video and if you like what you see, take a look at his blog post. Definitely worthwhile if you do a lot of shell work. And, of course, you can stay in Emacs while you’re doing it.

It’s Advent of Code time again and, as is his wont, Mike Zamansky is meeting the challenge and blogging about his results. Even better, he’s posted a video on his solutions to the first two problems.

The video isn’t about Emacs directly but, of course, all the work is done in Emacs. Because Zamansky mostly uses Clojure for his hobbyist programming, he uses the Cider package for his programming and the video serves as a nice illustration of using Cider and Emacs as a very nice programming environment.

Although the video is nominally about Clojure, his solutions would work, mutatis mutandis, with any Lisp. He uses the threading macros, which although not strictly necessary make things a little clearer. If you program in any of the Lisps, you’ll almost certainly enjoy the video and his solutions to the problems.

Irreal readers know that Zamansky is planning to retire at the end of the Spring semester but if he continues to produce videos like this one, we’ll all be pleased. Even if the videos aren’t specifically about Emacs, it’s useful to see examples of using Emacs to solve real problems. Regardless, enjoy this video and let Zamansky know you liked it so we can guilt encourage him to produce more. I always learn a lot from his videos and hope he produces more.