futhark-mode for Emacs

See the file futhark-mode.el. This Emacs mode provides:

• syntax highlighting
• automatic indentation
• interaction with an inferior futhark repl process

For IDE-like features, try Eglot, which works well with Futhark's built-in LSP server futhark lsp.

Installation

You can install this mode with Emacs' package manager. Enable the https://melpa.org/ archive, and install the futhark-mode package. Alternatively, add the following lines to your Emacs init file:

(add-to-list 'load-path "path/to/futhark-mode")
(require 'futhark-mode)

Usage

This mode is pretty straightforward and does not provide a lot of bells and whistles. But it does have some commands:

• C-c C-l (futhark-load-file) loads the current file into futhark repl, creating a new instance if a current one does not exist.

You may also want to use the futhark fmt integration with commands like futhark-fmt-buffer, or whenever you save with futhark-fmt-on-save-mode. You can enable that automatically on load as well:

(add-hook 'futhark-mode-hook futhark-fmt-on-save-mode)

Eglot

You can start Eglot automatically whenever you edit a Futhark file by adding

(add-hook 'futhark-mode-hook 'eglot-ensure)

to your init file.

Testing (for developers)

Run tools/test-indentation to test if the auto-indentation works. If you find a piece of code that futhark-mode cannot indent properly, please fix it, and put a small example in the tools/test-corpus directory to ensure that it doesn't break in the future.

Note that not all of the indentation examples in tools/test-corpus are necessarily ideal. Some of them exemplify behaviour that we would like to fix (but exist as a regression test to avoid even worse outcomes).

Additionally, you can symlink the tools/git-hooks/pre-commit hook into your local .git/hooks directory to automatically check your changes before each commit.

Authors

• Niels G. W. Serup
• Rasmus Wriedt Larsen
• Troels Henriksen

Reloading when hacking on the code

Add the directory containing the .el files to your load path with

(add-to-list 'load-path "/.../futhark-mode")
(require 'futhark-dev)

and then enter M-x RET futhark-dev-reload RET whenever needed.