Setting up a development environment for Gerbil Scheme and Doom Emacs¶

There is an installation guide and a page about development with Emacs in the Gerbil Scheme website, but I felt it was centered on plain Emacs and not on variants like Doom Emacs – which is fine, of course, I just happen to prefer Doom because it has a focus on Vim keybindings and I am much more used to them than to plain Emacs chords.

Install Gerbil¶

This one is easy: use the Hombrew formula. It also pulls in the underlying Gambit Scheme dependency.

$ brew install gerbil-scheme

Install `gerbil-mode` and `gambit-mode`¶

Both Gerbil and Gambit offer Emacs support as single Elisp files that live inside their respective project directory tree. They intend these files to be copied or symlinked into ~/.emacs.d and required in .emacs.

I found it easier to install them as “Github recipes” with Doom’s package! macro.

Within .doom.d/packages.el, add:

(package! gerbil-mode
  :recipe (:host github :repo "vyzo/gerbil"
           :files ("etc/gerbil-mode.el")))

(package! gambit-mode
  :recipe (:host github :repo "gambit/gambit"
           :files ("misc/gambit.el")))

Configure the new modes¶

There is a full example of a use-package configuration in the page linked above from Gerbil’s documentation. I have adapted it to configure separately both modes, only taking the minimal required setups.

Within .doom.d/config.el, add:

(use-package gambit-mode
  :defer t
  :config
  (add-hook 'inferior-scheme-mode-hook 'gambit-inferior-mode))

(use-package gerbil-mode
  :defer t
  :config
  (defvar gerbil-program-name
    ;; depending on your env setup, this can probably be just "gxi"
    (expand-file-name "/usr/local/bin/gxi"))
  (setq scheme-program-name gerbil-program-name))

Redefine key bindings¶

Most of the useful key bindings that Gerbil-mode and Gambit-mode expose are behind a “C-c” prefix. In Doom, hitting that key chord with a Schme file open (file extension “.scm” or “.ss”) will show all available key bindings on a which-key minibuffer. I have redfined some of them to be also available under the local leader key, which is defined elsewhere in my config to ,.