GNU ELPA - flymake-codespell

This is a codespell backend for Flymake in Emacs, used to automatically highlight errors as you type. It requires Emacs version 26.1 or newer.

Unlike most other spellcheckers, codespell does not have a dictionary of known words. Instead it has a list of common typos, and checks only for those. This means that it's far less likely to generate false positives, especially when used on source code, or any file with a lot of specific terms like documentation or research.

First, install codespell on your system. For example, if you're using Debian GNU/Linux, run this command in a terminal:

sudo apt install codespell

Once codespell is installed, install this package by typing the following in Emacs:

M-x package-install RET flymake-codespell RET

You must make sure the flymake-codespell-setup-backend function is called in the modes where you want to use it. For example, to make sure it is run in all programming language modes, add the following line to your init file:

(add-hook 'prog-mode-hook 'flymake-codespell-setup-backend)

You can substitute prog-mode-hook for any mode hook. For example, to add it to all text modes:

(add-hook 'text-mode-hook 'flymake-codespell-setup-backend)

You must also make sure flymake is enabled in the same modes. Type M-x flymake-mode to enable it for the running session, or set up hooks. For example:

(add-hook 'prog-mode-hook 'flymake-mode)

See the Flymake manual for more details.

The use-package can simplify your init file, and is available out-of-the-box starting with Emacs 29.1. For older versions, you must first install use-package. Here is a use-package declaration that you can copy into your init file:

(use-package flymake-codespell
  :ensure t
  :hook (prog-mode . flymake-codespell-setup-backend))

This enables flymake-codespell in all programming language modes, and automatically installs it the next time you restart Emacs, if it isn't already.

To add this to several modes, use something like the following:

(use-package flymake-codespell
  :ensure t
  :hook ((prog-mode . flymake-codespell-setup-backend)
         (text-mode . flymake-codespell-setup-backend)))

Here's a use-package declaration to unable flymake in the same modes:

(use-package flymake
  :hook (prog-mode text-mode))

To customize flymake-codespell, type:

M-x customize-group RET flymake-codespell RET

If you prefer adding customizations to your init file, try setting the variables flymake-codespell-program and flymake-codespell-program-arguments. These are their default values:

(setq flymake-codespell-program "codespell")
(setq flymake-codespell-program-arguments "")

You could also use this use-package declaration:

(use-package flymake-codespell
  :ensure t
  :custom ((flymake-codespell-program "codespell")
           (flymake-codespell-program-arguments ""))
  :hook ((prog-mode . flymake-codespell-setup-backend)
         (text-mode . flymake-codespell-setup-backend)))

Here are some alternatives to flymake-codespell:

• flyspell-prog-mode, which comes with Emacs out-of-the-box.

This library is part of GNU ELPA and therefore requires a copyright assignment to the Free Software Foundation for any non-trivial contributions.

Please email me a patch, or open a pull request on GitHub, according to your preferences.

You can find the latest version of flymake-codespell here:

https://www.github.com/skangas/flymake-codespell

Bug reports, comments, and suggestions are welcome! Send them to Stefan Kangas <stefankangas@gmail.com> or report them on GitHub.