Formatters

This page is a reference containing details on how to configure formatters, before you read — first check out how to add your first formatter.

---

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 ↗

A list of languages and how to configure their respective formatters.

Go

Gofumpt

Gofumpt support is built-in into gopls, which is Go’s language server.

[language-server.gopls.config]
gofumpt = true

Bash

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.

shfmt

Note

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

Nix

Nixfmt

[[language]]
auto-format = true
name = "nix"
formatter = { command = "nixfmt" }

Haskell

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 = [] }

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)" ] }

Laravel

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

Python

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

Black

• black is an opinionated formatter for Python

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

JSON

Deno

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

Prettier

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

JavaScript

JavaScript, TypeScript, JSX and TSX

Prettier

[[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

Deno

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

Markdown

Deno

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

Prettier

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

Fish

fish_indent

fish_indent is built into fish!

The following has been tested:

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

Fortran

fprettify

https://github.com/pseewald/fprettify ↗

A formatter for modern Fortran code.

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

GDScript

gdformat

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

A formatter for GDScript.

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

OCaml

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.

HTML and CSS

Prettier

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

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

Yaml

Prettier

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

SQL

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

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.

Ruby

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

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

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"] }

TOML

Taplo

https://github.com/tamasfe/taplo ↗

A versatile, feature-rich TOML toolkit.

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

Typst

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

Java

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

Gnome XML Library

Format XML files using GNOME XML library ↗ (libxml2)

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

Tidy

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"] }

Lua

StyLua

Format lua files using StyLua ↗

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