Racket v9.1

I've been using Racket to work through The Little Learner[1] and it's been a good experience. You need minimal Racket to work through the book (lambda, let, define, map; I think that's about it). But I branched out to learn more about the language and the standard library, and it's a fun and surprisingly powerful system to explore.

The biggest downside of Racket is that you can't build up your environment incrementally the way you can with Common Lisp/Sly. When you change anything in your source you reload REPL state from scratch. After CL it feels incredibly limiting in a Lisp. Incremental buildup is so valuable, if I wanted to do any Lisp work again I'd reach for CL before Racket just for this reason.

BTW, the book is _great_. Quick, easy to get through, very easy to understand, and teaches you everything from soup to nuts. If you're familiar with lisps you can get through the book in two weeks. It's then easy to get into any deep learning tutorial or project you want, or even start implementing some papers. The book manages not to water down the material despite not using any math at all. Although if you know some linear algebra or multivariable calculus you'll appreciate the beauty of the field more.

[1] https://www.thelittlelearner.com/

I learned recently that Racket is an accepted language on LeetCode, which solved the problem “when am I ever going to write lisp in real life…” for me. It’s provided a great excuse.

I have really been enjoying writing it! Paredit and SLIME are addictive.

Brings memories of when I did some chapters of HTDP2 to learn Lisp.

https://htdp.org/2024-11-6/Book/index.html

More accesible than SICP, highly recommended

posted by Stephen De Gabrielle and John Clements

We are pleased to announce Racket v9.1 is now available from https://download.racket-lang.org/.

As of this release:

Documentation organization and navigation can be specialized by language family, to allow users to interact with documentation in a way that is tailored to that language family. This is currently used by Rhombus.
The for form and its variants accept an #:on-length-mismatch specifier. 3.18 Iterations and Comprehensions: for, for/list, …
DrRacket improves the GUI for choosing color schemes.
DrRacket has curved syntax arrows. The degree of curvature indicates the relative left- or right-displacement of the arrow’s target.
DrRacket’s “Insert Large Letters” uses characters that match the comment syntax of the buffer’s language, making it useful (and fun!) in Rhombus.
The exn-classify-errno maps network and filesystem error numbers on various platforms to posix-standard symbols, to enable more portable code. 10.2 Exceptions
The behavior of Racket BC on certain character operations (most notably eq?) is changed to match that of Racket CS, with a small performance penalty for these operations for BC programs. 19 Performance 1.5 Implementations
The make-struct-type procedure can inherit the current inspector using a 'current flag. This is the default behavior, but there are situations in which it’s not possible to refer to the current inspector. 5.2 Creating Structure Types
Bundle configurations can better control the conventions for locating shared object files with the --enable-sofind=<conv> flags.
The system-type function can report on platform and shared-object-library conventions with new flags. 15.8 Environment and Runtime Information
The openssl/legacy library makes it possible to access OpenSSL’s built-in “legacy” provider, to get access to insecure and outdated algorithms. OpenSSL: Secure Communication
Typed Racket improves expected type propagation for keyword argument functions.
There are many other repairs and documentation improvements!

Don’t forget to run raco pkg migrate 9.0

Thank you

The following people contributed to this release:

Alexander Shopov, beast-hacker, Bob Burger, Brad Lucier, Cadence Ember, David Van Horn, evan, François-René Rideau, Gustavo Massaccesi, Jacqueline Firth, Jade Sailor, Jason Hemann, Jens Axel Søgaard, John Clements, Jonas Rinke, Matthew Flatt, Matthias Felleisen, Mike Sperber, Noah Ma, Pavel Panchekha, Rob Durst, Robby Findler, Ryan Culpepper, Sam Tobin-Hochstadt, Stephen De Gabrielle, and Wing Hei Chan.

Racket is a community developed open source project and we welcome new contributors. See racket/README.md to learn how you can be a part of this amazing project.

Feedback Welcome

Questions and discussion welcome at the Racket community on Discourse or Discord.

If you can - please help get the word out to users and platform specific repo packagers

Racket - the Language-Oriented Programming Language - version 9.1 is now available from https://download.racket-lang.org

See https://blog.racket-lang.org/2026/02/racket-v9-1.html for the release announcement and highlights.

Brings memories of when I did some chapters of HTDP2 to learn Lisp.

https://htdp.org/2024-11-6/Book/index.html

More accesible than SICP, highly recommended

[1] https://www.thelittlelearner.com/

> The biggest downside of Racket is that you can't build up your environment incrementally the way you can with Common Lisp/Sly. When you change anything in your source you reload REPL state from scratch.

I don’t quite understand… I’m using Racket in emacs/SLIME and I can eval-last-sexp, regions, etc.

The Little Learner is a great book. I tried rewriting all the code in Python/JAX while following the Scheme code style as closely as possible, and it worked out great.

The appendix on autodiff is a bit rushed, in my opinion. But in all fairness, the number of pages would probably need to be doubled to give a proper exposition of autodiff.

I think no Lisp is a "true" Lisp if it doesn't provide two critical components of the Lisp experience:

- Live Images

- REPL-driven development

That's why Clojure/Racket and even Scheme are Lisp-y but not a true Lisp. The only true Lisp languages I've found are CL and Janet.

I learned recently that Racket is an accepted language on LeetCode, which solved the problem “when am I ever going to write lisp in real life…” for me. It’s provided a great excuse.

I have really been enjoying writing it! Paredit and SLIME are addictive.

> LeetCode

> ...real life...

    (≠ "LeetCode" "real life")

The Little Learner is a great book. I tried rewriting all the code in Python/JAX while following the Scheme code style as closely as possible, and it worked out great.

The appendix on autodiff is a bit rushed, in my opinion. But in all fairness, the number of pages would probably need to be doubled to give a proper exposition of autodiff.

I don’t quite understand… I’m using Racket in emacs/SLIME and I can eval-last-sexp, regions, etc.

Ah, I'm using racketmode which doesn't support live state buildup (and the builtin GUI doesn't either). What exactly is your setup? SLIME only has a Common Lisp backend, it doesn't support Racket to my knowledge.

EDIT: ok with geiser and geiser-racket incremental state buildup works really well. I rescind my objection!

I think no Lisp is a "true" Lisp if it doesn't provide two critical components of the Lisp experience:

- Live Images

- REPL-driven development

That's why Clojure/Racket and even Scheme are Lisp-y but not a true Lisp. The only true Lisp languages I've found are CL and Janet.

Is this not ultimately a late-binding issue? Maybe I'm missing something, but I've absolutely been able to incrementally build up an environment without resetting using nrepl and Clojure

You are not a true LISP unless you use M-Expressions like the LISP 1.5 manual from the 1960s says. S-Expressions are inauthentic.

> LeetCode

> ...real life...

    (≠ "LeetCode" "real life")

For sure. I just meant having some motivating purpose to write Racket.

You are not a true LISP unless you use M-Expressions like the LISP 1.5 manual from the 1960s says. S-Expressions are inauthentic.

Is this not ultimately a late-binding issue? Maybe I'm missing something, but I've absolutely been able to incrementally build up an environment without resetting using nrepl and Clojure

For sure. I just meant having some motivating purpose to write Racket.

EDIT: ok with geiser and geiser-racket incremental state buildup works really well. I rescind my objection!

I think that should work in racket-mode as well. You can easily send individual sexps to the repl and add to the live state. However, one thing that CL does that Racket doesn't do (afaik) is when you change a data type (e.g. alter a struct), it automatically ensures live code uses the new types. In Racket by contrast I have to either carefully go through all affected forms and send them to the repl, or send the whole buffer to the repl. This does make the whole experience feel more static than in CL.

Oh, my mistake. I'm using Spacemacs and it looks like it's just using racket-mode..?

https://www.spacemacs.org/layers/+lang/racket/README.html

I'm guessing via swank: https://github.com/mbal/swank-racket

Oh, my mistake. I'm using Spacemacs and it looks like it's just using racket-mode..?

https://www.spacemacs.org/layers/+lang/racket/README.html

I'm guessing via swank: https://github.com/mbal/swank-racket

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