External formatter configuration

Helix can use external formatting programs available in the system $PATH.

Add these settings to languages.toml inside your config directory
auto-format = true and other language settings are inherited from languages.toml, there is no need to repeat them
Specifying an external formatter will replace any formatting supplied by the language server
Windows users may need to specify the full path to the executable

AWK

GNU AWK can pretty-print scripts, which can be used as a formatter.

[[language]]
name = "awk"
formatter = { command = "awk", timeout = 5, args = [ "--file=/dev/stdin", "--pretty-print=/dev/stdout" ] }

On macOS, GNU AWK installed via Homebrew is named gawk to not conflict with the system awk. Adjust the configuration accordingly.

Black

black is an opinionated formatter for Python

[[language]]
name = "python"
formatter = { command = "black", args = ["--quiet", "-"] }
auto-format = true

Blade

Blade Formatter

An opinionated blade template formatter for Laravel that respects readability.

[[language]]
name = "blade"
roots = ["composer.json", "index.php"]
formatter = { command = "blade-formatter", args = ["--write", "--stdin", "--wrap-line-length", "9999", "--wrap-attributes", "preserve-aligned"] }
auto-format = true

Ruff

The Ruff formatter is an extremely fast Python code formatter designed as a drop-in replacement for Black.

[[language]]
name = "python"
formatter = { command = "ruff", args = ["format", "--line-length", "88", "-"] }
auto-format = true

Deno

https://deno.land/

As of v1.25.0 these languages are supported:

ts, tsx, js, jsx, md, json, jsonc

Deno's formatter is written in Rust and is very fast in comparison to Prettier. The formatting options are mostly copied from Prettier, but there are some differences.

To see available formatting options: deno fmt --help
markdown does not support formatting as many languages in fenced code blocks as Prettier

The following have been tested:

[[language]]
name = "javascript"
formatter = { command = 'deno', args = ["fmt", "-", "--ext", "js" ] }
auto-format = true

[[language]]
name = "json"
formatter = { command = 'deno', args = ["fmt", "-", "--ext", "json" ] }

[[language]]
name = "markdown"
formatter = { command = 'deno', args = ["fmt", "-", "--ext", "md" ] }
auto-format = true

[[language]]
name = "typescript"
formatter = { command = 'deno', args = ["fmt", "-", "--ext", "ts" ] }
auto-format = true

[[language]]
name = "jsx"
formatter = { command = 'deno', args = ["fmt", "-", "--ext", "jsx" ] }
auto-format = true

[[language]]
name = "tsx"
formatter = { command = 'deno', args = ["fmt", "-", "--ext", "tsx" ] }
auto-format = true

fish_indent

fish_indent is built into fish!

The following has been tested:

[[language]]
name = "fish"
formatter = { command = "fish_indent" }
auto-format = true

fourmolu

https://github.com/fourmolu/fourmolu

Fourmolu is a formatter for Haskell source code. It is a fork of Ormolu, with the intention to continue to merge upstream improvements.

[[language]]
name = "haskell"
auto-format = true
formatter = { command = "zsh", args = ["-c", "fourmolu --stdin-input-file $(pwd)" ] }

fprettify

https://github.com/pseewald/fprettify

A formatter for modern Fortran code.

[[language]]
name = "fortran"
formatter = { command = "fprettify" , args = ["--stdout"] }
auto-format = true

gdformat

https://github.com/Scony/godot-gdscript-toolkit

A formatter for GDScript.

[[language]]
name = "gdscript"
formatter = { command = "gdformat", args = ["-"] }
auto-format = true

ocamlformat

https://github.com/ocaml-ppx/ocamlformat

[[language]]
name = "ocaml"
formatter = { command = "ocamlformat", args = ["-q", "--name=foo.ml", "-"] }
auto-format = true

The --name argument is required by ocamlformat when reading from stdin. foo.ml is a dummy value, the file does not have to exist for the formatter to work.

Prettier

https://prettier.io/

As of v2.8.4 these languages are supported:

The following have been tested (assuming prettier is in your PATH env-var):

[[language]]
name = "markdown"
formatter = { command = 'prettier', args = ["--parser", "markdown"] }

[[language]]
name = "html"
formatter = { command = 'prettier', args = ["--parser", "html"] }

[[language]]
name = "json"
formatter = { command = 'prettier', args = ["--parser", "json"] }

[[language]]
name = "css"
formatter = { command = 'prettier', args = ["--parser", "css"] }

[[language]]
name = "javascript"
formatter = { command = 'prettier', args = ["--parser", "typescript"] }
auto-format = true

[[language]]
name = "typescript"
formatter = { command = 'prettier', args = ["--parser", "typescript"] }
auto-format = true

[[language]]
name = "tsx"
formatter = { command = 'prettier', args = ["--parser", "typescript"] }
auto-format = true

[[language]]
name = "yaml"
formatter = { command = 'prettier', args = ["--parser", "yaml"] }
auto-format = true

If you've installed it locally only, it won't be in PATH, so replace all command = 'prettier' by command = 'npx' and add "prettier" as the 1st element of args.

Note

For Windows you may need to add .cmd to the command, example:

command = 'prettier.cmd'

RuboCop

A Ruby static code analyzer and formatter, based on the community Ruby style guide.

[[language]]
name = "ruby"
config = { solargraph = { diagnostics = true, formatting = false } }
formatter = { command = "bundle", args = ["exec", "rubocop", "--stdin", "foo.rb", "-a", "--stderr", "--fail-level", "fatal"] }
auto-format = true

Argument explanations:

--stdin foo.rb: RuboCop requires a filename for its reports, this is a dummy value to fulfill this. Call it whatever. Make it your own. Have fun with it.
--stderr: RuboCop absolutely ALWAYS prints any errors it identifies. This sends them to stderr, otherwise they'd show up in your editor.
--fail-level: Any error in the RuboCop formatter will fail with error code "1." This can prevent your files from saving. Raising the fail-level to "fatal" will leave it on just for cases were RuboCop is not working at all.

The "config" block will prevent diagnostics from also breaking if formatting fails.

If not using RuboCop via Bundler, you can modify the formatter command accordingly (omitting the bundle exec prepend):

formatter = { command = "rubocop", args = ["--stdin", "foo.rb", "-a", "--stderr", "--fail-level", "fatal"] }

shfmt

Since Bash Language Server 5.3.0 shfmt formatting is built into the language server, so you don't need this config if you have the shfmt binary installed

https://github.com/mvdan/sh#shfmt or https://github.com/patrickvane/shfmt

shfmt formats shell programs
To see available formatting options: shfmt -h

The following have been tested:

4 spaces:

[[language]]
name = "bash"
indent = { tab-width = 4, unit = "    " }
formatter = { command = 'shfmt', args = ["-i", "4"] }
auto-format = true

tabs:

[[language]]
name = "bash"
indent = { tab-width = 4, unit = "\t" }
formatter = { command = "shfmt" }
auto-format = true

StandardRB

A Ruby formatter that supports very little configuration so we can stop arguing about format and get on with our jobs. It's a wrapper around Rubocop so commands are basically identical.

[[language]]
name = "ruby"
formatter = { command = "bundle", args = ["exec", "standardrb", "--stdin", "foo.rb", "--fix", "--stderr"] }
auto-format = true

stylish-haskell

https://github.com/haskell/stylish-haskell

A simple Haskell code prettifier. This tool tries to help where necessary without getting in the way.

[[language]]
name = "haskell"
auto-format = true
formatter = { command = "stylish-haskell", args = [] }

sqlformat

https://github.com/andialbrecht/sqlparse

You can install sqlparse with pip to make the sqlformat command available.

[[language]]
name = "sql"
formatter = { command = "sqlformat", args = ["--reindent", "--indent_width", "2", "--keywords", "upper", "--identifiers", "lower", "-"] }

swift-format

https://github.com/apple/swift-format

swift-format provides the formatting technology for SourceKit-LSP and the building blocks for doing code formatting transformations.

[[language]]
name = "swift"
formatter = { command = "swift-format", args = ["format"] }
auto-format = true

note: older version of swift-format does not seem to work with helix (e.g. v0.50500.0). v509.0.0 verified as working.

SyntaxTree

Another formatting option for Ruby is SyntaxTree, which is used "under the hood" by Prettier for Ruby. It provides a few configuration options, either passed in as arguments or with a local .streerc file.

[[language]]
name = "ruby"
formatter = { command = "bundle", args = ["exec", "stree", "format"] }
auto-format = true

Taplo

https://github.com/tamasfe/taplo

A versatile, feature-rich TOML toolkit.

[[language]]
name = "toml"
formatter = { command = "taplo", args = ["format", "-"] }
auto-format = true

typstfmt

https://github.com/astrale-sharp/typstfmt

Basic formatter for the Typst language with a future.

[[language]]
name = "typst"
formatter = { command = "typstfmt", args = ["--output", "-"] }
auto-format = true

google-java-format

https://github.com/google/google-java-format

Java code formatter. Reformats Java source code to comply with Google Java Style.

Create a shell script with the content below with execution permission, include it in the PATH to use four spaces instead of tabs.

#!/usr/bin/env bash

$JAVA_HOME/bin/java -jar <path-to-jar-file>/google-java-format-1.21.0-all-deps.jar -a $1

In languages.toml file:

[[language]]
name = "java"
indent = { tab-width = 4, unit = "    " }
formatter = { command = "google-java-format", args = ["-"] }
auto-format = true

XML

Format XML files using GNOME XML library (libxml2)

[[language]]
name = "xml"
auto-format = true
formatter = { command = "xmllint", args = ["--format", "-"] }

Or using tidy

[[language]]
name = "xml"
formatter = { command = "tidy", args = ["-q", "-xml", "--show-errors", "0", "--show-warnings", "0", "--force-output", "--indent", "auto",  "--vertical-space", "yes", "--tidy-mark", "no", "-wrap", "120"] }

StyLua

Format lua files using StyLua

[[language]]
name = "lua"
formatter = { command = "stylua", args = [ "-" ] }

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