stylish-haskell
Haskell code prettifier https://github.com/jaspervdj/stylish-haskell
| Version on this page: | 0.9.2.1 |
| LTS Haskell 13.8: | 0.9.2.1 |
| Stackage Nightly 2019-01-27: | 0.9.2.1 |
| Latest on Hackage: | 0.9.2.1 |
Module documentation for 0.9.2.1
- Language
- Language.Haskell
- Language.Haskell.Stylish
- Language.Haskell.Stylish.Step
- Language.Haskell.Stylish
- Language.Haskell
stylish-haskell
Introduction
A simple Haskell code prettifier. The goal is not to format all of the code in a file, since I find those kind of tools often “get in the way”. However, manually cleaning up import statements etc. gets tedious very quickly.
This tool tries to help where necessary without getting in the way.
Installation
You can install it using stack install stylish-haskell or cabal install stylish-haskell.
You can also install it using your package manager:
- Debian 9 or later:
apt-get install stylish-haskell - Ubuntu 16.10 or later:
apt-get install stylish-haskell - Arch Linux:
pacman -S stylish-haskell
Features
- Aligns and sorts
importstatements - Groups and wraps
{-# LANGUAGE #-}pragmas, can remove (some) redundant pragmas - Removes trailing whitespace
- Aligns branches in
caseand fields in records - Converts line endings (customizable)
- Replaces tabs by four spaces (turned off by default)
- Replaces some ASCII sequences by their Unicode equivalents (turned off by default)
Feature requests are welcome! Use the issue tracker for that.
Example
Turns:
{-# LANGUAGE ViewPatterns, TemplateHaskell #-}
{-# LANGUAGE GeneralizedNewtypeDeriving,
ViewPatterns,
ScopedTypeVariables #-}
module Bad where
import Control.Applicative ((<$>))
import System.Directory (doesFileExist)
import qualified Data.Map as M
import Data.Map ((!), keys, Map)
data Point = Point
{ pointX, pointY :: Double
, pointName :: String
} deriving (Show)
into:
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TemplateHaskell #-}
module Bad where
import Control.Applicative ((<$>))
import System.Directory (doesFileExist)
import Data.Map (Map, keys, (!))
import qualified Data.Map as M
data Point = Point
{ pointX, pointY :: Double
, pointName :: String
} deriving (Show)
Configuration
The tool is customizable to some extent. It tries to find a config file in the following order:
- A file passed to the tool using the
-c/--configargument .stylish-haskell.yamlin the current directory (useful for per-directory settings).stylish-haskell.yamlin the nearest ancestor directory (useful for per-project settings)stylish-haskell/config.yamlin the platform’s configuration directory (on Windows, it is %APPDATA%, elsewhere it defaults to~/.configand can be overridden by theXDG_CONFIG_HOMEenvironment variable; useful for user-wide settings).stylish-haskell.yamlin your home directory (useful for user-wide settings)- The default settings.
Use stylish-haskell --defaults > .stylish-haskell.yaml to dump a
well-documented default configuration to a file, this way you can get started
quickly.
VIM integration
Since it works as a filter it is pretty easy to integrate this with VIM.
You can call
:%!stylish-haskell
and add a keybinding for it.
Or you can define formatprg
:set formatprg=stylish-haskell
and then use gq.
Alternatively, vim-autoformat supports stylish-haskell. To have it automatically reformat the files on save, add to your vimrc:
autocmd BufWrite *.hs :Autoformat
" Don't automatically indent on save, since vim's autoindent for haskell is buggy
autocmd FileType haskell let b:autoformat_autoindent=0
There is also the vim-stylish-haskell plugin, which runs stylish-haskell automatically when you save a Haskell file.
Emacs integration
haskell-mode for Emacs supports stylish-haskell. For configuration,
see the “Using external formatters” section of the
haskell-mode manual.
Atom integration
ide-haskell for Atom supports stylish-haskell.
atom-beautify for Atom supports Haskell using stylish-haskell.
Visual Studio Code integration
stylish-haskell-vscode for VSCode supports stylish-haskell.
Using with Continuous Integration
You can quickly grab the latest binary and run stylish-haskell like so:
curl -sL https://raw.github.com/jaspervdj/stylish-haskell/master/scripts/latest.sh | sh -s .
Where the . can be replaced with the arguments you pass to stylish-haskell.
Credits
Written and maintained by Jasper Van der Jeugt.
Contributors:
- Chris Done
- Hiromi Ishii
- Leonid Onokhov
- Michael Snoyman
- Mikhail Glushenkov