gleam-ts-mode: An Emacs Major Mode for Gleam

This mode uses tree-sitter (and Emacs 29's treesit package) under-the-hood for syntax highlighting and code navigation. If you're using an Emacs that's older than 29 (run M-x version to find out), or a version compiled without treesit (run M-: (treesit-available-p) to find out), you probably want gleam-mode instead.

gleam-mode.mp4

Setup

This project is hosted on MELPA, and this is the recommended way to install the package. To add MELPA as a package repository, add the following to your Emacs init file:

(require 'package)
;; Add MELPA to archives
(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/"))
;; Load and activate packages
(package-initialize)

use-package (recommended)

Add the following to your Emacs init file:

(use-package gleam-ts-mode
  :mode (rx ".gleam" eos))

vanilla

Install with

M-x package-install RET gleam-ts-mode RET

(M-x stands for "meta + x" which indicates holding the meta key (usually labeled "Alt") and tapping "x". Where you see RET you should press your "Enter" or "Return" key).

To load the package, run the following (or place it in your Emacs init file):

(require "gleam-ts-mode")
(add-to-list 'auto-mode-alist '("\\.gleam\\'" . gleam-ts-mode))

Install the Tree-Sitter Grammar

Unless you have the Gleam tree-sitter grammar installed and treesit knows where to find it, you'll want to run M-x gleam-ts-install-grammar. It should only take a moment, but does require that your OS has a C compiler available.

TODO

• Syntax highlighting
• Indentation
• Imenu integration
• Formatting
• Completion?
• REPL?

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gleam-mode: An Alternative Emacs Major Mode for Gleam

This mode uses tree-sitter alongside tree-sitter-mode and tree-sitter-indent for syntax highlighting and code navigation.

gleam-mode.mp4

Setup

The best way to install this is first to clone the project:

$ git clone --recurse-submodules git@github.com:gleam-lang/gleam-mode

Then you'll need to load this from your init script (~/.emacs or ~/.config/emacs/init.el).

use-package (recommended)

(use-package gleam-mode
  :load-path "~/path/to/gleam-mode")

Replace ~/path/to/gleam-mode with the path where you cloned gleam-mode.

vanilla

(add-to-list 'load-path "~/path/to/gleam-mode")
(load-library "gleam-mode")

Replace ~/path/to/gleam-mode with the path where you cloned gleam-mode.

Configuration

gleam-mode ships with a gleam-format command that is not bound by default to any keybinding. To bind it:

use-package

Add :bind (:map gleam-mode-map (<binding> . gleam-format)) to your use-package declaration. e.g.

(use-package gleam-mode
  :load-path "~/path/to/gleam-mode"
  :bind (:map gleam-mode-map
              ("C-c g f" . gleam-format)))

(here "C-c g f" means Control+C followed by g followed by f)

vanilla

Add the following after the lines where you setup gleam-mode:

(define-key gleam-mode-map (kbd "C-c g f") 'gleam-format)

(here "C-c g f" means Control+C followed by g followed by f)

automatically format on save

Alternatively, add these lines to your configuration to automatically run gleam-format on save:

    (add-hook 'gleam-mode-hook
              (lambda () (add-hook 'before-save-hook 'gleam-format nil t)))

TODO

• Syntax highlighting
• Indentation (at least somewhat)
• Formatting
• Completion?
• REPL?

License

This program is licensed under The Apache License, Version 2.0 or, at your option, under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. See LICENSE-apache for the terms of the Apache License, Version 2.0 or LICENSE-gpl for the terms of the GNU Public License, Version 3.