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Formatter Configurations

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askoa edited this page Oct 22, 2025 · 16 revisions

Introduction

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

Astro

You will also need to install https://www.npmjs.com/package/prettier-plugin-astro in your project

Prettier

name = "astro"
formatter = { command = "prettier", args = ["--plugin", "prettier-plugin-astro", "--parser", "astro"] }
auto-format = 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" ] }
auto-format = true

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

C and C++

clang-format

[[language]]
name = "c"
file-types = ["c", "h"]
formatter = { command = 'clang-format' }
auto-format = true

[[language]]
name = "cpp"
file-types = ["cpp", "cc", "cxx", "hpp", "hcc", "hxx"]
formatter = { command = 'clang-format' }
auto-format = true

C#

csharpier

https://csharpier.com/

[[language]]
auto-format = true
name = "c-sharp"
formatter = { command = "csharpier" }

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

Go

Gofumpt

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

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

[[language]]
name = "go"
auto-format = true

GraphQL

Prettier

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

Prettierd

[[language]]
name = "graphql"
formatter = { command = 'prettierd', args = [".graphql"] }
auto-format = true

Biome

[[language]]
name = "graphql"
formatter = { command = 'biome', args = ["format", "--stdin-file-path buffer.graphql"] }
auto-format = true

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

HTML and CSS

Prettier

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

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

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

Prettierd

[[language]]
name = "html"
formatter = { command = 'prettierd', args = [".html"] }
auto-format = true

[[language]]
name = "css"
formatter = { command = 'prettierd', args = [".css"] }
auto-format = true

[[language]]
name = "scss"
formatter = { command = 'prettierd', args = [".scss"] }
auto-format = true

Deno

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

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

Biome

Note

Biome currently does not support .scss or .html formatting

[[language]]
name = "css"
formatter = { command = 'biome', args = ["format", "--stdin-file-path", "buffer.css"] }
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

JavaScript (JS), TypeScript (TS), 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

Prettierd

Prettierd runs prettier as a daemon, with significant performance improvements

[[language]]
name = "javascript"
formatter = { command = 'prettierd', args = [".js"] }
auto-format = true

[[language]]
name = "typescript"
formatter = { command = 'prettierd', args = [".ts"] }
auto-format = true

[[language]]
name = "jsx"
formatter = { command = 'prettierd', args = [".jsx"] }
auto-format = true

[[language]]
name = "tsx"
formatter = { command = 'prettierd', args = [".tsx"] }
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

Biome

[[language]]
name = "javascript"
formatter = { command = 'biome', args = ["format", "--stdin-file-path", "buffer.js"] }
auto-format = true

[[language]]
name = "typescript"
formatter = { command = 'biome', args = ["format", "--stdin-file-path", "buffer.ts"] }
auto-format = true

[[language]]
name = "jsx"
formatter = { command = 'biome', args = ["format", "--stdin-file-path", "buffer.jsx"] }
auto-format = true

[[language]]
name = "tsx"
formatter = { command = 'biome', args = ["format", "--stdin-file-path", "buffer.tsx"] }
auto-format = true

JSON and JSONC

Deno

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

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

Prettier

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

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

Prettierd

[[language]]
name = "json"
formatter = { command = 'prettierd', args = [".json"] }
auto-format = true

[[language]]
name = "jsonc"
formatter = { command = 'prettierd', args = [".jsonc"] }
auto-format = true

Biome

[[language]]
name = "json"
formatter = { command = 'biome', args = ["format", "--stdin-file-path", "buffer.json"] }
auto-format = true

[[language]]
name = "jsonc"
formatter = { command = 'biome', args = ["format", "--stdin-file-path", "buffer.jsonc"] }
auto-format = true

Just

[[language]]
name = "just"
auto-format = true
formatter = { command = "just", args = ['--justfile', '/dev/stdin', '--dump'] }

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

Lua

StyLua

Format lua files using StyLua

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

Markdown

Deno

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

dprint

[[language]]
name = "markdown"
formatter = { command = "dprint", args = ["fmt", "--stdin", "md"] }
auto-format = true

Prettier

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

Prettierd

[[language]]
name = "markdown"
formatter = { command = 'prettierd', args = [".md"] }
auto-format = true

Nix

Nixfmt

[[language]]
name = "nix"
formatter = { command = "nixfmt" }
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.

Python

Ruff

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

Black

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

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"] }

Rust

dioxus fmt

dioxus fmt can format the rsx! macro:

[[language]]
name = "rust"
formatter = { command = "bash", args = ["-c", "rustfmt | dx fmt -f -"] }

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", "-"] }
auto-format = true

Svelte

You will also need to install https://www.npmjs.com/package/prettier-plugin-svelte in your project

Prettier

name = "svelte"
formatter = { command = "prettier", args = ["--plugin", "prettier-plugin-svelte", "--parser", "svelte"] }
auto-format = true

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.

TOML

Taplo

https://github.com/tamasfe/taplo

A versatile, feature-rich TOML toolkit.

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

Note

taplo (with the lsp feature) can format files, but not buffers. And even the files that it should format, may trigger "this document has been excluded", which disables formatting. So that config is necessary if you always want formatting.

Typst

typstyle

https://github.com/Enter-tainer/typstyle

Beautiful and reliable typst formatter

[[language]]
name = "typst"
formatter.command = "typstyle"
auto-format = true

typstfmt (unmaintained)

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

XML

Gnome XML Library

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

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"] }
auto-format = true

Yaml

dprint

[[language]]
name = "yaml"
formatter = { command = "dprint", args = ["fmt", "--stdin", "yaml"] }
auto-format = true

Prettier

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

Prettierd

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