Posts tagged "clojure":

The Genius of Lisp

I have just read the book The Genius of Lisp by Cees de Groot. It was a very interesting read. The book tells the history of the Lisp programming language from 1958 to today and also how Lisp, as one of the earliest high level programming languages, has influenced other programming languages over the years. It also goes into the technical details of how Lisp dialects were implemented and the differences between them. And it explains the mathematical groundwork by Alonso Church and Alan Turing for the Lambda calculus, and how John McCarthy used it to build his language.

The technical details are well explained and as easy to follow as they possibly might be. There is example code in IBM 704 Assembly with explanations, practical implementation examples in JavaScript that is easy for present-day programmers to follow, explanations in pseudocode and of course lots of code examples in various Lisp dialects. The early chapters on the mathematical underpinnings of lambda calculus and the foundational work for Lisp and its practical implementation gave me a proper understanding of it even if my mathematical knowledge is very limited.

For me personally, I felt that after reading the book, I now have a better understanding of the different dialects of Lisp, who created them and for what purpose. I knew about some of the dialects and some of their traits, but I learned a lot more about them. For instance, I did not know that Common Lisp is a thoroughly object oriented language and this surprised me.

Although I knew about the previous AI hype with "expert systems" and the AI winter that coincided with the economic downturn in the late 1980s, the book enlightened me with more details and more about its consequences for the AI language Lisp. We are fast heading into a new AI winter now since the LLM providers have unsustainable business models, but I think the consequences for Python will be less dire since its growth in popularity started long before the present LLM craze and it is less closely tied to AI research than Lisp was. (I bet on Python when I studied at the only Norwegian University or College that taught it instead of Java as their first language and since then, its popularity has only grown, from at that time being less used than Java and C#, but now being the second most used language after JavaScript/TypeScript according to Stack Overflow Survey.)

Reading The Genius of Lisp has strengthened my belief in Lisp as a brilliant programming language worth exploring further. It is not on the top 20 list of programming languages now, but it is powerful and elegant with its homoiconic s-expressions for both code and data. Learning more about the different dialects through the book also further convinced me of my previously somewhat uninformed hunch that Clojure and Scheme are Lisps I should look into further. (I am already a Guix user thanks to David Wilson's brilliant SystemCrafter videos, but I haven't had the time to delve deeper into Scheme.) My first meeting with Lisp was in Emacs, and I will continue to play with Emacs Lisp as well.

All in all, it was a good read and I highly recommend this book to people interested in programming, computer history and the mathematical underpinnings of functional programming, the Lambda calculus. Some previous knowledge of JavaScript is useful for understanding the implementation of Lisp functions in the early chapters.

Fix error with Cider Clojure REPL in Emacs on Guix

I am currently reading Clojure for the brave and true by Daniel Higginbotham and in Chapter 2 about how to use Emacs for Clojure, there are instructions on how to set up Emacs with Cider, a Clojure REPL. I tried installing the package with a use-package configuration with :ensure t and I got the package. However, when I tried using it as the book instructed, I just got an error. I then realised the need for OpenJDK and Clojure and installed those with my home-config.scm file in Guix. I tried again and I still got the same error. I then tried installing emacs-cider from Guix as well with the hope that maybe there was some kind of incompatibility between OpenJDK, Clojure and Cider that was ironed out in the guix package. It still did not work.

I tried looking up the error and found a blog post that suggested installing OpenJDK non-Guixily by downloading a binary and adding it to the $PATH which solved the problem for that user. I did not really want this, since I really like the idea of installing my whole system with a scheme file or two in a reproducible way. (I'm not there yet, but I hope to get there over time. I just started using Guix as my main distro a few weeks ago. For now, after installing Guix System or Guix on another distro, I do some manual work and then run a Shell script to set up a few folders and run the command that applies my home-config.)

Tonight, a day later, I DuckDuckWent again and found another blog post about Clojure that told me that since there are three outputs for the openjdk package, to get everything I would need for Clojure, I should install openjdk:jdk, not simply openjdk which would give me openjdk:out. In addition, I also added openjdk:doc since I am a fan of having as much documentation as possible available on my local machine. I saw a video where that documentation was read from inside Cider a couple of days ago, so I thought it might come in handy. Come to think of it, maybe that was accessed over the internet, not from the local machine. Anyway, it doesn't hurt to have some documentation.

And now, everything just works. Turns out the problem was just user error. Whenever there are multiple outputs of a package in Guix, it is important to know what you get with each output and choose accordingly. As someone who just recently switched my main machine to Guix, this is very useful information that I had not seen before. I thought I would write this up in a blog post so people out there trying to fix the same problem have a chance of finding a solution faster than I did, and for my own future reference.