# hindent [![Hackage](https://img.shields.io/hackage/v/hindent.svg?style=flat)](https://hackage.haskell.org/package/hindent) [![Build Status](https://travis-ci.org/chrisdone/hindent.png)](https://travis-ci.org/chrisdone/hindent)

Extensible Haskell pretty printer. Both a library and an
executable.

## Install

    $ stack install

## Usage

    hindent is used in a pipeline style:

    $ cat path/to/sourcefile.hs | hindent > outfile.hs

## Emacs

In
[elisp/hindent.el](https://github.com/chrisdone/hindent/blob/master/elisp/hindent.el)
there is `hindent-mode`, which provides keybindings to reindent parts of the
buffer:

- `M-q` reformats the current declaration.  When inside a comment, it fills the
  current paragraph instead, like the standard `M-q`.
- `C-M-\` reformats the current region.

To enable it, add the following to your init file:

```lisp
(add-to-list 'load-path "/path/to/hindent/elisp")
(require 'hindent)
(add-hook 'haskell-mode-hook #'hindent-mode)
```

## Vim

The `'formatprg'` option lets you use an external program (like hindent) to
format your text. Put the following line into ~/.vim/ftplugin/haskell.vim
to set this option for Haskell files:

    setlocal formatprg=hindent

Then you can format with hindent using `gq`. Read `:help gq` and `help
'formatprg'` for more details.

Note that unlike in emacs you have to take care of selecting a sensible buffer region as input to
hindent yourself. If that is too much trouble you can try [vim-textobj-haskell](https://github.com/gilligan/vim-textobj-haskell) which provides a text object for top level bindings.

## Atom

Basic support is provided through [atom/hindent.coffee](https://github.com/chrisdone/hindent/blob/master/atom/hindent.coffee). Mode should be installed as package into `.atom\packages\${PACKAGE_NAME}`,
here is simple example of atom [package](https://github.com/Heather/atom-hindent).