fourmolu
A formatter for Haskell source code
https://github.com/fourmolu/fourmolu
Version on this page: | 0.15.0.0@rev:1 |
LTS Haskell 22.33: | 0.14.0.0 |
Stackage Nightly 2024-09-07: | 0.15.0.0@rev:1 |
Latest on Hackage: | 0.16.2.0 |
fourmolu-0.15.0.0@sha256:2c4179e32c5226d903393f0d71cb2d845d5277a07b2df9e58efdc6e777b61ca8,6959
Module documentation for 0.15.0.0
- Ormolu
- Ormolu.Config
- Ormolu.Diff
- Ormolu.Exception
- Ormolu.Fixity
- Ormolu.Imports
- Ormolu.Parser
- Ormolu.Printer
- Ormolu.Printer.Combinators
- Ormolu.Printer.Comments
- Ormolu.Printer.Internal
- Ormolu.Printer.Meat
- Ormolu.Printer.Meat.Common
- Ormolu.Printer.Meat.Declaration
- Ormolu.Printer.Meat.Declaration.Annotation
- Ormolu.Printer.Meat.Declaration.Class
- Ormolu.Printer.Meat.Declaration.Data
- Ormolu.Printer.Meat.Declaration.Default
- Ormolu.Printer.Meat.Declaration.Foreign
- Ormolu.Printer.Meat.Declaration.Instance
- Ormolu.Printer.Meat.Declaration.OpTree
- Ormolu.Printer.Meat.Declaration.RoleAnnotation
- Ormolu.Printer.Meat.Declaration.Rule
- Ormolu.Printer.Meat.Declaration.Signature
- Ormolu.Printer.Meat.Declaration.Splice
- Ormolu.Printer.Meat.Declaration.Type
- Ormolu.Printer.Meat.Declaration.TypeFamily
- Ormolu.Printer.Meat.Declaration.Value
- Ormolu.Printer.Meat.Declaration.Warning
- Ormolu.Printer.Meat.ImportExport
- Ormolu.Printer.Meat.Module
- Ormolu.Printer.Meat.Pragma
- Ormolu.Printer.Meat.Type
- Ormolu.Printer.Operators
- Ormolu.Printer.SpanStream
- Ormolu.Processing
- Ormolu.Terminal
- Ormolu.Utils
- Paths_fourmolu
Fourmolu
- Configuration
- Installation
- Building from source
- Usage
- Troubleshooting
- Limitations
- Contributing
- License
Fourmolu is a formatter for Haskell source code. It is a fork of Ormolu, with upstream improvements continually merged.
We share all bar one of Ormolu’s goals:
- Using GHC’s own parser to avoid parsing problems caused by
haskell-src-exts
. - Let some whitespace be programmable. The layout of the input influences the layout choices in the output. This means that the choices between single-line/multi-line layouts in certain situations are made by the user, not by an algorithm. This makes the implementation simpler and leaves some control to the user while still guaranteeing that the formatted code is stylistically consistent.
- Writing code in such a way so it’s easy to modify and maintain.
- That formatting style aims to result in minimal diffs.
- Choose a style compatible with modern dialects of Haskell. As new Haskell extensions enter broad use, we may change the style to accommodate them.
- Idempotence: formatting already formatted code doesn’t change it.
- Be well-tested and robust so that the formatter can be used in large projects.
- ~~Implementing one “true” formatting style which admits no configuration.~~ We allow configuration of various parameters, via CLI options or config files. We encourage any contributions which add further flexibility.
Configuration
See https://fourmolu.github.io/config/
Installation
To install the latest release from Hackage, simply install with Cabal or Stack:
$ cabal install fourmolu
$ stack install fourmolu
Building from source
$ cabal build -fdev
$ stack build --flag fourmolu:dev
The dev
flag may be omitted in your local workflow as you work, but CI may not pass if you only build without the dev
flag.
Usage
The following will print the formatted output to the standard output.
$ fourmolu Module.hs
Add -i
(or --mode inplace
) to replace the contents of the input file with the formatted output.
$ fourmolu -i Module.hs
Specify a directory to recursively process all of its .hs
files:
$ fourmolu -i src
Or find all files in a project with git ls-files
:
$ fourmolu --mode inplace $(git ls-files '*.hs')
# Or to avoid hitting command line length limits and enable parallelism (12-way here):
$ git ls-files -z '*.hs' | xargs -P 12 -0 fourmolu --mode inplace
To check if files are already formatted (useful on CI):
$ fourmolu --mode check src
:zap: Beware git’s core.autocrlf
on Windows :zap:
Fourmolu’s output always uses LF line endings. In particular,
fourmolu --mode check
will fail if its input is correctly formatted
except that it has CRLF line endings. This situation can happen on Windows
when checking out a git repository without having set core.autocrlf
to false
.
Web app
See https://fourmolu.github.io/ to try Fourmolu in your browser. This is re-deployed on every new commit to main
, so will use the latest version of Fourmolu, potentially including unreleased changes.
Editor integration
Fourmolu can be integrated with your editor via the Haskell Language Server. Just set haskell.formattingProvider
to fourmolu
(instructions).
GitHub actions
[run-fourmolu
][https://github.com/haskell-actions/run-fourmolu] is the recommended way to ensure that a project is formatted with Fourmolu.
Language extensions, dependencies, and fixities
Fourmolu automatically locates the Cabal file that corresponds to a given
source code file. Cabal files are used to extract both default extensions
and dependencies. Default extensions directly affect behavior of the GHC
parser, while dependencies are used to figure out fixities of operators that
appear in the source code. Fixities can also be overridden via the fixities
configuration option in fourmolu.yaml
. When the input comes from
stdin, one can pass --stdin-input-file
which will give Fourmolu the location
that should be used as the starting point for searching for .cabal
files.
Here is an example of the fixities
configuration:
fixities:
- infixr 9 .
- infixr 5 ++
- infixl 4 <$
- infixl 1 >>, >>=
- infixr 1 =<<
- infixr 0 $, $!
- infixl 4 <*>, <*, *>, <**>
It uses exactly the same syntax as usual Haskell fixity declarations to make it easier for Haskellers to edit and maintain.
fourmolu.yaml
can also contain instructions about
module re-exports that Fourmolu should be aware of. This might be desirable
because at the moment Fourmolu cannot know about all possible module
re-exports in the ecosystem and only few of them are actually important when
it comes to fixity deduction. In 99% of cases the user won’t have to do
anything, especially since most common re-exports are already programmed
into Fourmolu. (You are welcome to open PRs to make Fourmolu aware of more
re-exports by default.) However, when the fixity of an operator is not
inferred correctly, making Fourmolu aware of a re-export may come in handy.
Here is an example:
reexports:
- module Control.Lens exports Control.Lens.At
- module Control.Lens exports "lens" Control.Lens.Lens
Explicit package names are allowed in re-export declarations (see the example above).
Finally, all of the above-mentioned parameters can be controlled from the command line:
- Language extensions can be specified with the
-o
or--ghc-opt
flag. - Dependencies can be specified with the
-p
or--package
flag. - Fixities can be specified with the
-f
or--fixity
flag. - Re-exports can be specified with the
-r
or--reexport
flag.
Searching for .cabal
files can be disabled by passing
--no-cabal
.
Magic comments
Fourmolu understands two magic comments:
{- FOURMOLU_DISABLE -}
and
{- FOURMOLU_ENABLE -}
This allows us to disable formatting selectively for code between these
markers or disable it for the entire file. To achieve the latter, just put
{- FOURMOLU_DISABLE -}
at the very top. Note that for Fourmolu to work the
fragments where Fourmolu is enabled must be parseable on their own. Because of
that the magic comments cannot be placed arbitrarily, but rather must
enclose independent top-level definitions.
{- ORMOLU_DISABLE -}
and {- ORMOLU_ENABLE -}
, respectively, can be used to the same effect,
and the two styles of magic comments can be mixed.
Regions
One can ask Fourmolu to format a region of input and leave the rest
unformatted. This is accomplished by passing the --start-line
and
--end-line
command line options. --start-line
defaults to the beginning
of the file, while --end-line
defaults to the end.
Exit codes
Exit code | Meaning |
---|---|
0 | Success |
1 | General problem |
2 | CPP used (deprecated) |
3 | Parsing of original input failed |
4 | Parsing of formatted code failed |
5 | AST of original and formatted code differs |
6 | Formatting is not idempotent |
7 | Unrecognized GHC options |
8 | Cabal file parsing failed |
9 | Missing input file path when using stdin input and accounting for .cabal files |
10 | Parse error while parsing fixity overrides |
100 | In checking mode: unformatted files |
101 | Inplace mode does not work with stdin |
102 | Other issue (with multiple input files) |
400 | Failed to load Fourmolu configuration file |
Using as a library
The fourmolu
package can also be depended upon from other Haskell programs.
For these purposes only the top Ormolu
module should be considered stable.
It follows PVP starting from the version
0.10.2.0. Rely on other modules at your own risk.
Troubleshooting
Operators are being formatted weirdly!
This can happen when Ormolu doesn’t know or can’t determine the fixity of an operator.
-
If this is a custom operator, see the instructions in the Language extensions, dependencies, and fixities section to specify the correct fixities in a
.ormolu
file. -
If this is a third-party operator (e.g. from
base
or some other package from Hackage), Ormolu probably doesn’t recognize that the operator is the same as the third-party one.Some reasons this might be the case:
- You might have a custom Prelude that re-exports things from Prelude
- You might have
-XNoImplicitPrelude
turned on
If any of these are true, make sure to specify the reexports correctly in a
.ormolu
file.
You can see how Ormolu decides the fixity of operators if you use --debug
.
Limitations
- CPP support is experimental. CPP is virtually impossible to handle correctly, so we process them as a sort of unchangeable snippets. This works only in simple cases when CPP conditionals surround top-level declarations. See the CPP section in the design notes for a discussion of the dangers.
- Various minor idempotence issues, most of them are related to comments or column limits.
- Fourmolu is in a fairly early stage of development. The implementation should be as stable as Ormolu, as it only makes minimal changes, and is extensively tested. But the default configuration style may change in some minor ways in the near future, as we make more options available. It will always be possible to replicate the old default behaviour with a suitable
fourmolu.yaml
.
Contributing
If there are any options you’d like to see, let us know. If it’s not too complicated to implement (and especially if you implement it yourself!) then we’ll probably add it.
See DEVELOPER.md
for documentation.
License
See LICENSE.md.
Copyright © 2018–2020 Tweag I/O, 2020-present Matt Parsons
Acknowledgements
The vast majority of work here has been done by the Ormolu developers, and thus they deserve almost all of the credit. This project is simply intended as a haven for those of us who admire their work, but can’t quite get on board with some of their decisions when it comes down to the details.
Changes
Fourmolu 0.15.0.0
-
Add
single-deriving-parens
configuration option to determine ifderiving
clauses of a single type should be parenthesized (#386) -
Fix the order in which the configurations are applied (#390)
Upstream changes:
Ormolu 0.7.4.0
- Don’t error when the
JavaScriptFFI
language pragma is present. Issue 1087. - Improve comment placement in if-then-else blocks. Issue 998.
- Now command line options for fixity overrides and module re-exports
overwrite information from
.ormolu
files. Issue 1030. - Respect newlines in data declarations in more cases. Issue 1077 and issue 947.
- The
-d / --debug
command line option now makes Ormolu print out debug information regarding operator fixity inference. Issue 1060.
Fourmolu 0.14.1.0
-
Fix
single-constraint-parens: never
for nested quantified constraints (#374) -
Fix
column-limit
withBlockArguments
(#377) -
Fixed an issue where re-exporting a module with Haddock comments +
import-exports=leading
was indented too far (#381)
Upstream changes:
Ormolu 0.7.3.0
- Switched to
ghc-lib-parser-9.8
, with the following new syntactic features:
Fourmolu 0.14.0.0
-
Provide
resolvePrinterOpts
instead offillMissingPrinterOpts
-
Format configuration better in
--debug
output
Upstream changes:
Ormolu 0.7.2.0
-
Preserve necessary braces for final function arguments. Issue 1044.
-
Put
"this"
PackageImports
at the end. Issue 1048. -
Format parenthesized operators starting with a
#
correctly in the presence ofUnboxedSums
. Issue 1062. -
Fix false positives in AST diffing related to empty Haddock comments in data declarations. Issue 1065.
Fourmolu 0.13.1.0
- Fix
single-constraint-parens: never
withQuantifiedConstraints
(#340) - Fix issue with single documented export +
import-export-style: leading
(#341) - Fix reexports configuration not allowing repeated modules (#336)
Fourmolu 0.13.0.0
- Automatically ignore files in Cabal/Stack directories when recursively finding files to format.
Upstream changes:
Ormolu 0.7.1.0
-
Include
base
fixity information when formatting a Haskell file that’s not mentioned in an existing cabal file. Issue 1032 -
Update
displayException
forOrmoluException
to pretty print the exception. PR 1031. -
Ormolu is now aware of more common module re-exports by default.
-
Support explicit mention of target package name in module re-exports. Even if the exported package is not specified as a direct dependency of the component being formatted it will still be taken into account correctly. Issue 1037.
-
Ormolu no longer fails when CPP directly follows the import section (a regression introduced in 0.7.0.0). Issue 1040.
Ormolu 0.7.0.0
-
Inference of operator fixity information is now more precise and takes into account the import section of the module being formatted. Issue 892 and issue 929.
-
Ormolu can now be made aware of module re-exports through ~~either special declarations in
.ormolu
files~~ thereexports
configuration option (see the readme for a description of the syntax), or on the command line with the--reexport
/-r
option. Issue 1017. -
~~Ormolu now looks for
.ormolu
files independently of.cabal
files. This means that it is now possible to have one.ormolu
file for multiple Cabal packages. Issue 1019.~~ -
Consistently format
do
blocks/case
s/MultiWayIf
s with 4 spaces if and only if they occur as the applicand. Issue 1002 and issue 730. -
Support the (deprecated)
DatatypeContexts
extension to avoid surprises. Issue 1012. -
Don’t let comments escape from empty export lists. Issue 906.
-
Format
\cases
with multiple patterns across multiple lines correctly. Issue 1025.
Fourmolu 0.12.0.0
-
Add
single-constraint-parens
option for controlling parenthesis around constraints in type signatures. See issue 288 -
Add
column-limit
option to try to insert line breaks when lines exceed a certain length. May break idempotence in some particularly painful cases. See issue 71 -
Add a new CLI flag
--print-defaults
which makes fourmolu print default options to stdout. This can be used to generate default config which can be further tweaked by userfourmolu --print-defaults > fourmolu.yaml
. See issue 307
Upstream changes:
Ormolu 0.6.0.1
- Fix false positives in AST diffing related to
UnicodeSyntax
. PR 1009.
Ormolu 0.6.0.0
-
Haddocks attached to arguments of a data constructor are now formatted in the pipe style (rather than the caret style), consistent with everything else. As a consequence, now Ormolu’s output will be deemed invalid by the Haddock shipped with GHC <9.0. Issue 844 and issue 828.
-
Insert space before char literals in ticked promoted constructs when necessary. Issue 1000.
-
Switched to
ghc-lib-parser-9.6
:-
Extended
OverloadedLabels
:#Foo
,#3
,#"Hello there"
.Also, it is now disabled by default, as it causes e.g.
a#b
to be parsed differently. -
New extension:
TypeData
, enabled by default. -
Parse errors now include error codes, cf. https://errors.haskell.org.
-
-
Updated to
Cabal-syntax-3.10
. -
Now whenever Ormolu fails to parse a
.cabal
file it also explains why. PR 999.
Fourmolu 0.11.0.0
- Added the
no-space
value for thein-style
option. See issue 291
Upstream changes:
Ormolu 0.5.2.0
-
Eliminated the
fixity-th
Cabal flag because it caused issues on GHC 9.4 as well as on aarch64. See issue 941 and issue 927. -
Now operators without explicitly specified fixity default to left associativity and highest precedence. Issue 907.
Ormolu 0.5.3.0
-
Stop making empty
let
s move comments. Issue 917. -
Now
.ormolu
fixity override files can use both LF and CRLF line endings. PR 969. -
Normalize parentheses around constraints. Issue 264.
-
The
ormolu
function now consumesText
instead ofString
due to an internal refactoring. -
Exposed a more complete public API in the
Ormolu
module. The API is supposed to be stable and change according to PVP. -
Now warnings regarding Ormolu not being able to find
.cabal
files or finding such files but them not mentioning the source file in question are only displayed when--debug
is used. Printing the warnings by default seems to have been confusing, see e.g. Issue 971 and issue 924.
Fourmolu 0.10.1.0
- Fix bug where using
{-
in a single-line comment would wrongfully escape it (#265) - Fix idempotence bug with indented multiline comments (#273)
Fourmolu 0.10.0.0
New options:
- New
leading-args
option tofunction-arrows
configuration that allows leading arrows only for function arguments (#233) - Add
haddock-style-module
option (#135)
Improvements of existing options:
- Add unicode formatting for quasiquotes and arrow brackets (#261)
Bug fixes:
- Fix bug with
let-style
changing single-line let-in blocks indo
blocks to multiline. - Don’t consider the first space after
--
part of the comment (#255)
Upstream changes:
Ormolu 0.5.1.0
-
Imports are now sorted by package qualifier, if one is present. Issue 905.
-
Extension packs like
GHC2021
andHaskell2010
are now bumped to the top of the list of language pragmas. Issue 922. -
Fix formatting of
SCC
pragmas indo
blocks. Issue 925. -
Support type applications in patterns. Issue 930.
-
Handle
UnicodeSyntax
variants more consistently. Issue 934. -
Fix an inconsistency in formatting of types in GADT declarations in certain cases. PR 932.
-
Switched to
ghc-lib-parser-9.4
, which brings support for the following new syntactic features:\cases
viaLambdaCase
OPAQUE
pragmas- Unboxed sum type constructors like
(# | #)
.
-
Updated to
Cabal-syntax-3.8
, supportingcabal-version: 3.8
.
Fourmolu 0.9.0.0
New configuration options:
- Add
let-style
andin-style
configuration options (#229). The default is set tolet-style: auto
andin-style: right-align
, which should not reformat already formatted files (with some exceptions depending on comment placement), but allows users to format withnewline
without additional configuration. - Add
unicode
configuration (#206)
Bug fixes:
- Fix some edge cases with function arrows (#247)
- Fix formatting of module header + export lists when
WARNING
orDEPRECATED
pragma is present (#244) - Fixed a bug where an extra space was inserted before promoted types (e.g.
foo @'True
) (#211) - When
--respectful
is enabled, awhere
keyword on the line after the export list will not be moved up to the end of the previous line. (#167)
Fourmolu 0.8.2.0
- Add
multi-line-compact
option tohaddock-style
that will output{-|
for multiline haddocks instead of{- |
(#130) - Add
function-arrows
configuration option to style arrow placement in type signatures (#209)
Fourmolu 0.8.1.0
- Add
emptyConfig
(#221) - Fixed CLI options not overriding config file options, broken in 0.7.0.0 (#225)
Fourmolu 0.8.0.0
- Consolidate
import-export-comma-style
anddiff-friendly-import-export
into a new optionimport-export-style
(#201) - Accept folders as input (#213)
Upstream changes:
Ormolu 0.5.0.1
-
Fixed a bug in the diff printing functionality. Issue 886.
-
Indent closing bracket for list comprehensions in
do
blocks. Issue 893. -
Fix
hs-source-dirs: .
resulting in failing to find a.cabal
file for a Haskell source file. Issue 909. -
Comments in closed type family declarations are now indented correctly. Issue 913.
-
Cache
.cabal
file parsing and processing when given multiple input files in the same project. This results in dramatic speedups on projects which have both huge.cabal
files and a large number of individual modules. Issue 897.
Fourmolu 0.7.0.1
- Fix bad copy/paste where parsing errors for
haddock-style
would mentionCommaStyle
- Include relevant test files in sdist bundle
Fourmolu 0.7.0.0
-
Add
--quiet
flag to make the output quieter -
Removed
--cabal-default-extensions
flag; the behavior is now enabled by default -
Add
fixities
configuration tofourmolu.yaml
- See the notes in the Ormolu changelog below, except instead of providing fixity information in a
.ormolu
file, it should be in afixities
config option infourmolu.yaml
, e.g.
fixities: - 'infixr 8 .=' - 'infixr 5 #'
- See the notes in the Ormolu changelog below, except instead of providing fixity information in a
-
Fixed issue with
import-export-comma-style
for multiline import/export elements (#187) -
Multiline haddock comments with consecutive empty newlines will no longer report an “AST differs” error (#172)
Upstream changes:
Ormolu 0.5.0.0
-
Changed the way operator fixities and precedences are inferred.
- Ormolu now tries to locate
.cabal
files of source files by default and in addition to default extensions it also infers the list of dependencies. - Ormolu comes equipped with extensive knowledge of all packages on Hackage and operators that those packages define. Knowing the names of the dependencies it can select the right fixity and precedence info from its knowledge base.
- You can ask Ormolu not to look for
.cabal
files by using the--no-cabal
switch. - Dependencies can be selected manually by using the
-p / --package
option (can be repeated many times). - The default heuristic algorithm will still try to guess the right fixities and precedence.
- ~Fixity overrides can be provided by the user in the familiar Haskell
notation (e.g.
infixr 9 .
, one declaration per line). They are loaded by default from the.ormolu
file that is expected to be in the same directory as the.cabal
file of a given source file. However, if--no-cabal
is supplied, the.ormolu
file will not be looked for either.~ Fixity declarations can be also provided by using the-f / --fixity
command line option, which see. - This resolves the following issues: Issue 826, Issue 785, Issue 690, Issue 825.
- Ormolu now tries to locate
-
Invalid haddock comments are formatted in a more consistent way. Leading haddock triggers (
|
,^
) in an invalid haddock comment block are now escaped with a backslash\
. Issue 816. -
Type synonyms and families are now formatted correctly when the equals sign is preceded by a comment. Issue 829.
-
Bidirectional pattern synonyms are formatted nicer in certain cases. Issue 843.
-
Magic comments (like
{- ORMOLU_DISABLED -}
) now allow arbitrary succeeding text. This fixes use cases like Issue 856. -
Remove discrepancies between unboxed types and terms. Issue 856 .
- Unboxed sum types are now formatted with a space before each
|
. - Unboxed unit tuples on type and value levels are formatted as
(# #)
.
- Unboxed sum types are now formatted with a space before each
-
Errors caused by AST differences now print before/after diffs. Issue 877.
-
Improved formatting of data declarations in the case of single-constructor record with a Haddock. Issue 881.
Fourmolu 0.6.0.0
- Fixed regression in 0.5.0.0 with multiline tuples (#162)
- Fixed regression in 0.5.0.0 with multiline record types (#160)
- Fixed regression in 0.5.0.0 with indentation after a list comprehension (#149)
- Add
import-export-comma-style
configuration to allow leading commas in module import/export lists
Fourmolu 0.5.0.0
- Fixed issue with leading commas in guards (#123)
- Use trailing haddocks for record fields when using leading commas (#124)
Upstream changes:
Ormolu 0.4.0.0
-
When a guard is located on its own line, the body associated with this guard is indented by one extra level, so that it can easily be distinguished from the guard predicate or pattern. Issue 806.
-
Now a space is forced after
--
in line comments. Issue 808. -
Allow formatting Backpack signature files (
.hsig
). The switch between regular module mode and signature mode is based on the file extension by default, but can be overridden with the-t / --source-type
command line option. Issue 600. -
Blank Haddock comments are now eliminated. This also fixes issues with differing ASTs in some special cases. Issue 726.
-
Rewrite rules that are never active are now formatted correctly. Issue 823.
-
Promoted infix data constructors are now formatted correctly. Issue 768.
-
Switched to
ghc-lib-parser-9.2
. Issue 794.- Support for the new syntax-related language extensions:
OverloadedRecordDot
andOverloadedRecordUpdate
(disabled by default). Issue 709. - Removed support for
record-dot-preprocessor
. For the getter syntax, consider usingOverloadedRecordDot
instead. Issue 659. Issue 705. - Support for the
GHC2021
language.
- Support for the new syntax-related language extensions:
Ormolu 0.3.1.0
-
Allow check mode when working with stdin input. Issue 634.
-
Now guards are printed on a new line if at least one guard is multiline or if all guards together occupy more than one line. The body of each guard is also indented one level deeper in that case. Issue 712.
-
Invalid Haddock comments are no longer silently deleted, but rather converted into regular comments. Issue 474.
Fourmolu 0.4.0.0
- Write “Loaded config from” message to
stderr
instead ofstdout
(#42) - Fixed issue with multiline haddocks in indented contexts (#64)
- Avoid renaming magic comments (#90)
Upstream changes:
Ormolu 0.3.0.1
-
Improvements to
.cabal
file handling:- When looking for a
.cabal
file, directories were previously erroneously also considered. Issue 781. - We now print a note if Ormolu was told to consider
.cabal
files, but no suitable one could be found. - Handle an empty
hs-source-dirs
correctly. - Also consider modules which are only conditionally listed
in the
.cabal
file.
- When looking for a
-
The special handling of CPP is now only applied if CPP is actually enabled. Issue 782.
-
The left hand side of the
:
operator now uses braces if necessary. Issue 780.
Ormolu 0.3.0.0
-
Data declarations with multiline kind signatures are now formatted correctly. Issue 749.
-
Infix arrow command formations are formatted like usual operators. This fixes Issue 748.
-
do
arrow commands are formatted more flexibly. Fixes Issue 753. -
Source code is always read and written using UTF8 and ignoring the native line ending conventions. Issue 717.
-
Opt-in support to respect default-extensions and default-language from .cabal files. Issue 517.
-
Empty case expressions are now rendered with braces. Issue 765.
-
Omit braces on repeated application of
do
blocks. Issue 735. -
Improved handling of disabled regions. PR 773.
- Disabled regions are now exactly preserved, in particular empty lines and trailing spaces. Issue 673.
- Strings like
-}
can now be present in disabled regions. Issue 708.
This means that using CPP or magic comments in certain ways which were only supported as a side effect previously (like in Issue 601) will now result in formatting failures. Also see Issue 774.
Ormolu 0.2.0.0
-
Now standalone kind signatures are grouped with type synonyms. Issue 683.
-
TemplateHaskell
is not enabled by default anymore. Issue 699. -
Made record dot pre-processor rendering idempotent in certain specific cases. Issue 701.
-
Added support for arrow command application. Issue 716.
-
Switched to
ghc-lib-parser-9.0.1
. PR 722.- Support for the new language extensions:
LexicalNegation
,LinearTypes
: disabled by defaultQualifiedDo
: enabled by default
- Due to upstream changes in whitespace sensitity,
TypeApplications
is now enabled by default. Issue 452. - Haddocks on declarations in files without a
module
header are no longer deleted. Issue 480. - Due to a change in Haddock parsing, empty Haddock comments on function arguments now get deleted.
- Support for the new language extensions:
-
CTYPE pragmas are now preserved. Issue 689.
-
TypeApplications
in data/type family instances are now supported. Issue 698. -
Formatting infix arrow command formations now preserves the AST. Issue 718.
-
Surround code in brackets with spaces if it contains a
StarIsType
*
to prevent unparseable output. Issue 704. -
Formatting applied multiline constructs in do blocks now preserves the AST. Issue 707.
This will sometimes result in odd indentations, e.g. this snippet is a fixed point:
foo = do do (+1) 1
-
GHC options passed in via the CLI can now be overridden in local files. Previously, if an extension was disabled via the CLI, it could not be re-enabled per file.
-
NegativeLiterals
is no longer enabled by default. Also, spaces after negation via-
are removed where possible. Issue 694. -
Minus signs in literal patterns are now preserved in all cases. Issue 733.
-
Added support for left-to-right arrow application. Issue 737.
-
Now
--mode check
fails on missing trailing blank lines. Issue 743. -
Fixed indentation of arrow forms in do blocks. Issue 739.
Ormolu 0.1.4.1
- Added command line option
--color
to control how diffs are printed. Standardized the way errors are printed.
Ormolu 0.1.4.0
-
Added support for monad comprehensions. Issue 665.
-
Fixed a bug when a space was inserted in front of promoted types even when it wasn’t strictly necessary. Issue 668.
-
Now the checking mode displays diffs per file when unformatted files are found. The rendering of the diffs is also improved. Issue 656.
Ormolu 0.1.3.1
- Fixed a problem with multiline record updates using the record dot preprocessor. Issue 658.
Fourmolu 0.3.0.0
- New config option
newlines-between-decls
, to choose the number of blank lines between top-level declarations. - Minor CLI improvements. In particular, the set of valid values for each option is communicated more consistently.
Fourmolu 0.2.0.0
-
More consistent indentation. Previously, with indentation set to n, some constructs such as nested lists and tuples would use an ugly mix of n-space and 2-space indentation.
-
New configuration options (see README or Hackage docs for details):
comma-style
record-brace-space
indent-wheres
diff-friendly-import-export
respectful
haddock-style
Upstream changes:
Ormolu 0.1.3.0:
-
Ormolu no longer overwrites already formatted files. PR 649.
-
Now a space is guaranteed before ticked promoted types. Issue 631.
-
Made formatting of single-line explicitly bidirectional pattern synonyms idempotent. Issue 630.
Ormolu 0.1.2.0:
-
Fixed the bug when comments in different styles got glued together after formatting. Issue 589.
-
Added
-i
as a shortcut for--mode inplace
. Issue 467. -
Improved grouping of top-level declarations. Issue 466.
Fourmolu 0.1.1.0
Upstream changes:
Ormolu 0.1.1.0:
-
Imports in a import lists are now normalized: duplicate imports are combined/eliminated intelligently.
-
Import declarations that can be merged are now automatically merged. Issue 414.
-
The magic comments for disabling and enabling Ormolu now can encompass any fragment of code provided that the remaining code after exclusion of the disabled part is still syntactically correct. Issue 601.
-
Improved sorting of operators in imports. Issue 602.
-
Fixed a bug related to trailing space in multiline comments in certain cases. Issue 603.
-
Added support for formatting linked lists with
(:)
as line terminator. Issue 478. -
Fixed rendering of function arguments in multiline layout. Issue 609.
-
Blank lines between definitions in
let
andwhile
bindings are now preserved. Issue 554. -
Fixed the bug when type applications stuck to the
$
of TH splices that followed them. Issue 613. -
Improved region formatting so that indented fragments—such as definitions inside of
where
clauses—can be formatted. Issue 572. -
Fixed the bug related to the de-association of pragma comments. Issue 619.
Fourmolu 0.1.0.0
-
Allow configuration of indentation size via
fourmolu.yaml
config files. -
An operator on a new line is no longer indented when its left operand is a do-block. This prevents the AST from potentially changing when indenting by more than two spaces.
Upstream changes:
Ormolu 0.1.0.0:
-
Fixed rendering of type signatures concerning several identifiers. Issue 566.
-
Fixed an idempotence issue with inline comments in tuples and parentheses. Issue 450.
-
Fixed an idempotence issue when certain comments were picked up as “continuation” of a series of comments Issue 449.
-
Fixed an idempotence issue related to different indentation levels in a comment series. Issue 512.
-
Fixed an idempotence issue related to comments which may happen to be separated from the elements they are attached to by the equality sign. Issue 340.
-
Fixed an idempotence issue with type synonym and data declarations where the type has a Haddock. Issue 578.
-
Fix the false positive about AST differences in presence of comments with multiple blank lines in a row. Issue 518.
-
Fixed rendering of comments around if expressions. Issue 458.
-
Unnamed fields of data constructors are now documented using the
-- ^
syntax. Issue 445 and Issue 428. -
Fixed non-idempotent transformation of partly documented data definition. Issue 590.
-
Fixed an idempotence issue related to operators. Issue 522.
-
Renamed the
--check-idempotency
flag to--check-idempotence
. Apparently only the latter is correct.
Fourmolu 0.0.6.0
- The project was fourked to provide four space indent.
Ormolu 0.0.5.0
-
Grouping of statements in
do
-blocks is now preserved. Issue 74. -
Grouping of TH splices is now preserved. Issue 507.
-
Comments on pragmas are now preserved. Issue 216.
-
Ormolu can now be enabled and disabled via special comments. Issue 435.
-
Added experimental support for simple CPP. Issue 415.
-
Added two new options
--start-line
and--end-line
that allow us to select a region to format. Issue 516. -
Fixed rendering of module headers in the presence of preceding comments or Haddocks. Issue 561.
Ormolu 0.0.4.0
-
When given several files to format, Ormolu does not stop on the first failure, but tries to format all the files. Issue 502.
-
Made rendering of pattern matches involving operators consistent with other cases of rendering of operators. Issue 500.
-
More compact rendering of type family injectivity constraints. Issue 482.
-
Improved rendering of the keyword
where
in class, data, and type family declarations. When headers of these declarations are multi-linewhere
is now put on its own line. Issue 509. -
Fixed the bug pertaining to rendering of arrow notation with multiline expressions. Issue 513.
-
Made rendering of data type definitions, value-level applications, and application of types use the same style. Moreover, existential now doesn’t cause the data constructor be unconditionally rendered in multiline layout. Issue 427.
-
Records with a single data constructor are now formatted more compactly. Issue 425.
-
Switched to
ghc-lib-parser-8.10.1
. -
Implemented support for the new language extensions
ImportQualifiedPost
andStandaloneKindSignatures
.
Ormolu 0.0.3.1
- Fixed rendering of record updates with the record dot preprocessor syntax Issue 498.
Ormolu 0.0.3.0
-
Fixed an issue related to unnecessary use of curly braces. Issue 473.
-
Fixed the issue with formatting multi-way if when it happens to be a function applied to arguments Issue 488. This changed the way multi-line if is formatted in general.
-
Added support for record dot pre-processor when used via the plugin. Issue 486.
-
Stopped hanging record constructors and improved placing potentially-hanging consturctions in the presence of comments. Issue 447.
-
Fixed indentation in presence of type applications. Issue 493.
-
Class and instance declarations now do not have a blank line after
where
. Grouping of methods from the original input is also preserved with some normalizations. Issue 431.
Ormolu 0.0.2.0
-
Switched to
ghc-lib-parser
instead of depending on theghc
package directly. This should allow us to use newest features of GHC while not necessarily depending on the newest version of the compiler. In addition to that Ormolu is now GHCJS-compatible. -
Now unrecognized GHC options passed with
--ghc-opt
cause Ormolu to fail (exit code 7). -
Fixed formatting of result type in closed type families. See issue 420.
-
Fixed a minor inconsistency between formatting of normal and foreign type signatures. See issue 408.
-
Fixed a bug when comment before module header with Haddock was moved inside the export list. See issue 430.
-
Empty
forall
s are now correctly preserved. See issue 429. -
Fixed issue 446, which involved braces and operators.
-
When there are comments between preceding Haddock (pipe-style) and its corresponding declaration they are preserved like this in the output instead of being shifted. To be clear, this is not a very good idea to have comments in that position because the Haddock will end up not being associated with the declarations. Issues 440 and 448.
-
Implemented correct handling of shebangs. Issue 377.
-
Implemented correct handling of stack headers. Issue 393.
-
Sorting language pragmas cannot not change meaning of the input program anymore. Issue 404.
-
Fixed formatting of applications where function is a complex expression. Issue 444.
Ormolu 0.0.1.0
- Initial release.