hindent
Extensible Haskell pretty printer
https://github.com/commercialhaskell/hindent
Version on this page: | 5.2.3 |
LTS Haskell 22.39: | 6.1.1 |
Stackage Nightly 2024-10-31: | 6.2.0 |
Latest on Hackage: | 6.2.0 |
hindent-5.2.3@sha256:5b7be78995f86adc8131a718301ff78c81f23104e34e2376482b7b539d650283,3269
Module documentation for 5.2.3
hindent
Haskell pretty printer
Install
$ stack install hindent
Usage
$ hindent --help
hindent --version --help --style STYLE --line-length <...> --indent-size <...> --no-force-newline [-X<...>]* [<FILENAME>]
Version 5.1.1
Default --indent-size is 2. Specify --indent-size 4 if you prefer that.
-X to pass extensions e.g. -XMagicHash etc.
The --style option is now ignored, but preserved for backwards-compatibility.
Johan Tibell is the default and only style.
hindent is used in a pipeline style
$ cat path/to/sourcefile.hs | hindent
The default indentation size is 2
spaces. Configure indentation size with --indent-size
:
$ echo 'example = case x of Just p -> foo bar' | hindent --indent-size 2; echo
example =
case x of
Just p -> foo bar
$ echo 'example = case x of Just p -> foo bar' | hindent --indent-size 4; echo
example =
case x of
Just p -> foo bar
Customization
Create a .hindent.yaml
file in your project directory or in your
~/
home directory. The following fields are accepted and are the
default:
indent-size: 2
line-length: 80
force-trailing-newline: true
By default, HIndent preserves the newline or lack of newline in your input. With force-trailing-newline
, it will make sure there is always a trailing newline.
Emacs
In
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 standardM-q
.C-M-\
reformats the current region.
To enable it, add the following to your init file:
(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 which provides a text object for top level bindings.
In order to format an entire source file execute:
:%!hindent
Alternatively you could use the vim-hindent plugin which runs hindent automatically when a Haskell file is saved.
Atom
Fortunately, you can use https://atom.io/packages/ide-haskell with the path to hindent specified instead of that to stylish-haskell. Works like a charm that way!
Changes
5.2.3:
* Sort explicit import lists
* Report the `SrcLoc` when there's a parse error
* Improve long type signatures pretty printing
* Support custom line-break operators, add `--line-breaks` argument
* Fix infix data constructor
* Disable `RecursiveDo` and `DoRec` extensions by default
* Add RecStmt support
* Improve GADT records, data declaration records
* Complicated type alias and type signatures pretty printing
* Fix quasi-quoter names
5.2.2:
* Parallel list comprehensions
* Leave do, lambda, lambda-case on previous line of $
* Misc fixes
5.2.1:
* Fix hanging on large constraints
* Render multi-line comments
* Rename --tab-size to --indent-size
* Don't add a spurious space for comments at the end of the file
* Don't add trailing whitespace on <-
* Disable PatternSynonyms
* Put a newline before the closing bracket on a list
5.2.0:
* Default tab-width is now 2
* Supports .hindent.yaml file to specify alt tab-width and max
column
* Put last paren of export list on a new line
* Implement tab-size support in Emacs Lisp
5.1.1:
* Preserve spaces between groups of imports (fixes #200)
* Support shebangs (closes #208)
* Output filename for parse errors (fixes #179)
* Input with newline ends with newline (closes #211)
* Document -X (closes #212)
* Fix explicit forall in instances (closes #218)
* Put last paren of export list on a new line #227
5.1.0:
* Rewrote comment association, more reliable
* Added --tab-size flag for indentation spaces
* Fixed some miscellaneous bugs
5.0.1:
* Re-implement using bytestring instead of text
* Made compatible with GHC 7.8 through to GHC 8.0
* Added test suite and benchmarks in TESTS.md and BENCHMARKS.md
5.0.0:
* Drop support for styles
4.6.4
* Copy/delete file instead of renaming
4.4.6
* Fix whole module printer
* Accept a filename to reformat
4.4.5
* Fix bug in infix patterns
4.4.2
* Bunch of Gibiansky style fixes.
* Support CPP.
* Tibell style fixes.
4.3.8
* Fixed: bug in printing operators in statements.
4.5.4
* Improvements to Tibell style.
* 6x speed up on rendering operators.