Changelog

0.6.0

Released on 2026-08-24

Breaking changes

The JSON output produced with --output-format json has changed. In fix, the fields start and end are replaced by a field range that contains the two values (#650).

New and improved rules

New rules:
- condition_call (#503)
- condition_message (#545)
- empty_file (#477, @JosephBARBIERDARNAL)
- expect_s4_class (#553, @Yousa-Mirage)
- glue (#484, @novica)
- if_not_else (#551)
- literal_coercion (#504)
- missing_argument (#506)
- nested_pipe (#516)
- notin (#459, @Yousa-Mirage)
- pipe_consistency (#482)
- pipe_return (#502)
- rep_times_ignored (#556, @Yousa-Mirage)
- stopifnot_all (#547, @Yousa-Mirage)
- strings_as_factors (#546, @Yousa-Mirage)
- unnecessary_parentheses (#510, @JosephBARBIERDARNAL)
- unused_object (#589)
Improved rules:
- any_is_na now also reports NA %notin% x cases (#470, @Yousa-Mirage)
- equals_na now also reports x %notin% NA cases (#469, @Yousa-Mirage)
- expect_s3_class now also reports expect_true(is.<class>(x)), expect_true(inherits(x, class)), and dynamic class expressions. Dynamic class expressions are reported without an automatic fix (#555, @Yousa-Mirage).
- Four more functions skipped by default from implicit_assignment: expect_silent() (from testthat), expect_defunct() and expect_deprecated() (from lifecycle), and try() (#543, @maelle, #654).
- outdated_suppression now has a safe fix that removes the unused suppression comment (or comments if # jarl-ignore-start and # jarl-ignore-end are used) (#638).
- which_grepl now supports named which(x = ...) arguments and native pipe chains such as x |> grepl(pattern = ...) |> which(). Calls with additional which() arguments are reported without an automatic fix (#560, @Yousa-Mirage).

CLI improvements

The CLI now gives suggestions when some rule names don’t exist (#501).
New CLI argument --exclude to exclude files or directories from the checks, mirroring the exclude argument in jarl.toml (#520).
Passing --statistics in the CLI now indicates which violations have an automatic unsafe fix (#554).
Jarl now reports rule violations in files that contain syntax errors and provides clearer messages for syntax errors (#538, #569).
New --output-format sarif to export to SARIF (#508, @dieghernan).
Clearer output for jarl check --help (#521).
New command jarl rule <rule_name> to print a rule’s documentation in the terminal, for example jarl rule any_is_na (#566).
Jarl now provides shell completions for bash, zsh, fish, powershell, and elvish. See Shell completions for more information (#567).

TOML improvements

New argument [lint.per-file-ignores] in jarl.toml to deactivate rules on specific files (#500).
New argument skipped-functions for the true_false_symbol rule in jarl.toml to list functions whose arguments are allowed to contain the T and F symbols (#542).

Other improvements

Several new ways to install Jarl:
- it is available on PyPI under the name jarl-linter, enabling its installation via uv, pipx, and other tools (#466).
- it is available on conda-forge, enabling its installation via mise and pixi (@salim-b).
- it is available on Homebrew, enabling its installation via brew.
Fixed outdated paths in the contributing guide (#658, @christopherkenny).

Bug fixes

--statistics now reports syntax errors and returns a non-zero status when parsing fails (#577, @Yousa-Mirage).
--fix-only now implies --fix and no longer applies unsafe fixes by default (#579, @Yousa-Mirage).
Jarl now checks rule violations inside expressions on the left-hand side of [, [[, $, and @ (#581, @Yousa-Mirage).
true_false_symbol no longer reports T and F when they are used as objects in subset expressions, such as T[1:2] (#582, @Yousa-Mirage).
implicit_assignment no longer flags chained assignments like if (TRUE) a <- b <- 1, aligning with lintr behavior (#480, @atsyplenkov).
Automatic fixes now skip rewrites when comments are inside the rewritten expression, while still allowing leading and trailing comments (#461, @Yousa-Mirage).
Suppression comments in @examples and @examplesIf now work correctly (#443).
Fix alignment of diagnostic in console when source uses tabs (#445, #559).
Files that have “Generated by” in their first comment are ignored by Jarl (#486).
Fixed unreachable_code that was not running on braced expressions (#512).
Fixed false positives in assignment rule. Jarl could recommend replacing <- by = in places where this would change the meaning of the code (#515).
implicit_assignment now includes alist(), expect_no_condition(), expect_no_warning(), expect_no_error(), expect_no_message(), and expect_no_match() in the list of functions skipped by default (#527, #639).
Jarl no longer fails to parse ...() (#584, @Yousa-Mirage).
redundant_equals now skips cases that use rlang’s !! and !!! operators (#625).
The fix for comparison_negation is now considered “unsafe” because it can produce different output depending on operator precedence around the comparison (#632).
Fix the detection of Depends: R (>= x.y.z) in some cases (#641).
Replace panic by a proper error if jarl.toml is unreadable, for instance because of a permission error (#645).
Ensure the LSP has the same file selections and exclusions capabilities as the CLI (#647).

0.5.0

Released on 2026-03-24

Deprecations

The command-line argument --assignment and the jarl.toml argument assignment are both deprecated. Instead, you should use the following code in jarl.toml:
```
[lint.assignment]
operator = "<-" # or "="
```
More info on these rule-specific options in jarl.toml in the “Features” section below (#334).
The rule "browser" is deprecated. Calls to browser() are now detected with the rule "undesirable_function" (#336).

Features

jarl.toml now accepts rule-specific options in subsections [lint.<rule_name>], such as:

[lint]
...

# In the rule `duplicated_arguments`, do not report calls to `my_function()`
# and `list()` where multiple arguments have the same name.
[lint.duplicated_arguments]
extend-skipped-functions = ["my_function", "list"]

These options are listed in the Configuration page (#333).

Jarl now also analyzes piped functions, e.g. the following code is reported by the any_is_na rule:
```
is.na(x) |> any()

x |> is.na() |> any()
```
(#338).
Jarl now checks R code in more places:
- chunks in Quarto and R Markdown documents. More information in the “R Markdown and Quarto” section (#50).
- @examples and @examplesIf sections in roxygen2 comments (#385).
Added support for multiple jarl.toml, i.e. each file now uses the nearest jarl.toml. For example, Jarl can check a folder where several subfolders have their own jarl.toml (before, this would error). (#353)
New option include in jarl.toml, to complement exclude (#349).
New rules:
- dplyr_filter_out (#393)
- dplyr_group_by_ungroup (#395)
- duplicated_function_definition (#358)
- expect_match (#364, @bjyberg)
- expect_no_match (#368, @bjyberg)
- invalid_chunk_suppression (#350)
- nzchar (#406, @maelle)
- quotes (#381, @bjyberg)
- undesirable_function (replaces browser) (#336)
- unused_function (#362)
The output in terminal with output format full or concise is now organized in multiple sections (summary, warnings, notes) (#366).
Hovering a diagnostic now shows the rule name (#377).
Jarl can be used with pre-commit and prek, see Pre-commit tools (#379).
The CLI now errors early when some incompatible arguments are used (#437).

Bug fixes

fixed_regex could loop infinitely trying to add fixed = TRUE. This is fixed (#388).
Some fixes to ensure that automatic fixes don’t introduce new violations or new parsing errors (#389).
Suppression comments now work better when inserted in piped chains (#397).
Fix a wrong parsing error when using next() or break() (#417).

0.4.0

Released on 2026-02-05

Breaking changes

The support for comments to hide violations (aka suppression comments, aka # nolint comments in lintr) has been entirely reworked (#218). It is no longer compatible with lintr’s comments. Instead, Jarl now uses # jarl-ignore comments and follows different rules regarding the syntax and location of those comments. Detailed documentation is available in the section “Suppression comments” on the website. As part of this rewrite, the following rules have been added:
- blanket_suppression (#243)
- misnamed_suppression (#309)
- misplaced_file_suppression (#305)
- misplaced_suppression (#307)
- unexplained_suppression (#304)
- unmatched_range_suppression (#312)
- unused_suppression (#310)

Features

New CLI argument --statistics to show the number of violations per rule instead of the details of each violation. Jarl prints a hint to use this argument when more than 15 violations are reported (only when --output-format is concise or full). This value can be configured with the environment variable JARL_N_VIOLATIONS_HINT_STAT. (#250, #266)
Jarl now looks in parent folders for jarl.toml. It searches until the user config folder is reached (the location of this folder depends on the OS: ~/.config on Unix and ~/AppData/Roaming on Windows). Jarl uses the first jarl.toml that is found. This is useful to store settings that should be common to all projects (e.g. assignment = "<-") without creating a jarl.toml, which is a common situation for standalone R scripts. (#253)
New rules:
- equals_nan (#284)
- equals_null (#283)
- for_loop_dup_index (#327)
- if_always_true (#311, @bjyberg)
- internal_function (#291)
- redundant_ifelse (#260)
- unnecessary_nesting (#268)
- unreachable_code (#261)
When the output format is full or concise, rule names now have a hyperlink leading to the website documentation (#278).
any_is_na now reports NA %in% x (#286).

Other changes

The following rules are now disabled by default. They still exist and the user can choose to use them, but they were deemed too noisy for limited benefit to be enabled by default:
- assignment (#258)
- fixed_regex (#279)
- sample_int (#262)
equals_na now reports x %in% NA cases, as documented (#285).
There are now binaries available for linux-musl (x64 and arm64) (#287).

Bug fixes

When output-format is json or github, additional information displayed in the terminal (e.g. timing) isn’t included anymore to avoid parsing errors (#254).
Fixed a bug in the number of “fixable diagnostics” reported when the arg fixable is present in jarl.toml but --fix is not passed (#255).
fixed_regex is now correctly classified as “Performance” instead of “Readability” rule internally (#279).
Default values of function parameters are now analyzed too (#282).
duplicated_arguments doesn’t report anymore cases where argument names " and ' were conflated, e.g.
```
switch(x, `"` = "double", `'` = "single")
```
(#288).

Documentation

New section in the Integrations page to show how to use Jarl in various CI/CD platforms (#289, @philipp-baumann).

0.3.0

Released on 2025-12-17

Breaking changes

Jarl now excludes by default file paths matching the following patterns: .git/, renv/, revdep/, cpp11.R, RcppExports.R, extendr-wrappers.R, and import-standalone-*.R.

A new CLI argument --no-default-exclude can be used to check those files as well. This argument overrides the default-exclude = true option when set in jarl.toml (#178, @novica).

Features

--output-format json now contains two fields diagnostics and errors (#219).
Better support for namespaced function calls, both when reporting violations and when fixing them (#221).
The class_equals rule now also reports cases like identical(class(x), "foo") and identical("foo", class(x)) (#234).
New rules:
- expect_s3_class (#235)
- expect_type (#226)
- fixed_regex (#227)
- sprintf (#224)
- string_boundary (#225)
- vector_logic (#238)

Fixes

# nolint comments are now properly applied to nodes that are function arguments, e.g.
```
foo(
  # nolint
  any(is.na(x))
)
```
does not report a violation anymore (#229).

Other changes

expect_named no longer reports cases like expect_equal(x, names(y)) because rewriting those as expect_named(y, x) would potentially change the intent of the test and the way it is read (#220).

0.2.1

Released on 2025-11-29

Other

Important performance improvement when using --fix, in particular in projects with many R files (#217).

0.2.0

Released on 2025-11-28

Breaking changes

For consistency between CLI arguments and jarl.toml arguments, the following CLI arguments are renamed (#199):
- --select-rules becomes --select
- --ignore-rules becomes --ignore
- --assignment-op becomes --assignment

Features

New argument extend-select in jarl.toml and --extend-select in the CLI to select additional rules on top of the existing selection. This can be useful to select opt-in rules in addition to the default set of rules (#193).
Added support for seq and seq2 rules (#187).
Added support for several rules related to testthat. Those rules are disabled by default and can be enabled by combining select or extend-select with the rule name or the TESTTHAT group rule name. Those rules are:
- expect_length (#211)
- expect_named (#212)
- expect_not (#204)
- expect_null (#202)
- expect_true_false (#191)

Fixes

implicit_assignment no longer reports cases inside quote() (#209).

Documentation

Added section on Neovim to the Editors page (#188, @bjyberg).
Added page “Tutorial: add a new rule” (#183).

0.1.2

Released on 2025-11-23

Features

Added support for list2df rule (#179).
Added support for browser rule (#185, @jonocarroll).
Added support for system_file rule (#186).

Fixes

(Hopefully) Fixed wrong printing of ANSI characters in multiple terminals on Windows (#179, thanks @novica for the report).

Documentation

Added sections on RStudio and Helix to the Editors page.
Added installation instructions using Scoop on Windows.

0.1.1

Released on 2025-11-20

Fixes

Fix discovery of jarl.toml by the Jarl extension (#175, thanks @DavisVaughan for the report).
Rule duplicated_argument no longer reports cli_ functions where multiple arguments have the same name (#176, thanks @DavisVaughan for the report).

Documentation

The docs of assignment rule now explain how to change the preferred assignment operator.

0.1.0

Released on 2025-11-19

First release (announced)