Racket mode for GNU Emacs

This provides a major mode to edit Racket source files, as well as a major mode for a Racket REPL. The edit/run experience is similar to DrRacket.

• Focus on Racket.

  • Mode line and menu say Racket.
  • Omit stuff for various current and historical Schemes that's not applicable to Racket.

• Use DrRacket concepts where applicable.

  • A simple and obvious way to "run" a file.
  • Allow interaction in the REPL, but the effect is wiped on the next run.
  • A simple way to run unit tests (to run the test submodule).

• More thorough syntax highlighting ("font-lock"):

  • All Racket keywords, built-ins, self-evals, and so on.
  • All variations of define for functions and variables.

• Correct indentation of Racket forms, including for/fold and for*/fold.

• Compatible with Emacs 24.3+.

• More.

Caveats

• If you've used other Lisps and Schemes before, you might prefer Geiser, which is very sophisticated.

• Although I dogfood this -- use it constantly to code Racket -- it is beta quality. My total experience writing Emacs modes consists of writing this mode.

• Pull requests from smarter/wiser people are welcome.

• Please report issues here.

Install

The recommended way to use racket-mode is to install the package from MELPA. M-x package-install, racket-mode.

TIP: To use MELPA add the following to your ~/.emacs or ~/.emacs.d/init.el:

(require 'package)
(add-to-list 'package-archives
             '("melpa" . "http://melpa.org/packages/")
             t)

Configure

To start, there are only two variables you might need to set:

• racket-racket-program, the name or pathname of the Racket executable. This defaults to Racket.exe on Windows else racket.

• Set racket-raco-program, the name or pathname of the Raco executable. This defaults to Raco.exe on Windows else raco.

On Windows or Linux, these defaults will probably work for you.

On OS X, downloading Racket doesn't add its bin directory to your PATH. Even after you add it, GUI Emacs doesn't automatically use your path (unless you use the handy exec-path-from-shell package). Therefore you may want to set both of these to be full pathames.

You can setq these directly in your Emacs init file (~/.emacs or ~/.emacs.d/init.el), or, use M-x Customize, as you prefer.

Key bindings

To customize things like key bindings, you can use racket-mode-hook in your Emacs init file. For example, although F5 is bound to the racket-run command, let's say you wanted C-c r to be an additional binding:

(add-hook 'racket-mode-hook
          (lambda ()
            (define-key racket-mode-map (kbd "C-c r") 'racket-run)))

Documentation

Within Emacs, use the usual help functions.

• Type C-h m to get help about the modes in effect for the current buffer, including a list of key bindings and commands.

• To see help about a specific command, for example racket-run, type C-h f and then racket-run.

Here on GitHub you can browse the Reference.

Contributing

Pull requests are welcome! See CONTRIBUTING.md.

Background/Motivation

I started this project accidentally, while trying to figure out a font-lock issue with Quack under Emacs 24.2.

Knowing nothing about how to make a mode in Emacs, I tried to isolate the problem by making a simple major mode, then adding things until it broke. It didn't break and I ended up with this.

I took various .emacs.d hacks that I'd previously made to use with Quack, and rolled them into this mode.

Also, I'd recently spent time adding Racket fontification to the Pygments project, and wanted richer font-lock.

Also, I had experienced issues with enter! not always reloading modules in recent versions of Racket, and came up with a DrRacket-like alternative, run!.

Finally, I remembered that when I was new to Racket and Emacs, I got confused by the Scheme menu. It has options that work with various Schemes over the years, but which are N/A for Racket. I would stare it and wonder, "Um, how do I just 'run my program'??". I figured a fresh focus on Racket might be helpful, especially for other folks transitioning from using DrRacket.

Update, Jan 2014: After I had used this for a long time, putting up with its quirks, someone put it on MELPA. That nudged me to take another look, learn more about Elisp and Emacs modes, and improve it. Although I still feel like an amateur, it has probably improved from alpha to beta quality.

Please see the Acknowledgments.