antalsz / fourmolu.el

A configurable formatter for Haskell source code (based on vyorkin/ormolu.el)

fourmolu.el

Format Haskell source code using fourmolu. Requires reformatter.el.

See also Vasily Yorkin's ormolu.el, which this is based on.

Usage

With use-package:

(use-package fourmolu
 :hook (haskell-mode . fourmolu-format-on-save-mode)
 :bind
 (:map haskell-mode-map
   ("C-c r" . fourmolu-format-buffer)))

Without:

(push "~/.elib/contrib/reformatter.el" load-path)
(push "~/.elib/contrib/fourmolu.el" load-path)
(load-library "fourmolu")
(add-hook 'haskell-mode-hook 'fourmolu-format-on-save-mode)

Additional configuration

The package can be configured via the usual customize-group RET fourmolu mechanism. For example, to enable the TypeApplications extension by default, you can put ("--ghc-opt" "-XTypeApplications") under the "Fourmolu Extra Args" option (fourmolu-extra-args elisp var).

Notes

This package is a fork of vyorkin/ormolu.el, followed by the moral equivalent of s/ormolu/formolu/g plus a few other text updates (like this one).

This package is just a tiny wrapper on top of the reformatter.el, I mean really tiny, just a few lines of code.