Formatter and Linter Configuration

Add or configure formatters and linters in lua/plugins/format.lua.

Configuration Files

All formatting and linting is configured in lua/plugins/format.lua:

• conform.nvim - Formatting
• nvim-lint - Linting

Tools are installed via mason-tool-installer in lua/plugins/lsp.lua.

Adding a Formatter

1. Add to Mason Tool Installer

In lua/plugins/lsp.lua, add formatter to ensure_installed:

{
  'WhoIsSethDaniel/mason-tool-installer.nvim',
  opts = {
    ensure_installed = {
      -- ... existing tools
      'new-formatter',
    },
  },
}

2. Configure in conform.nvim

In lua/plugins/format.lua, add to formatters_by_ft:

{
  'stevearc/conform.nvim',
  opts = {
    formatters_by_ft = {
      -- ... existing formatters
      newlang = { 'formatter-name' },
    },
  },
}

3. Customize Formatter (Optional)

Add custom args in formatters table:

{
  'stevearc/conform.nvim',
  opts = {
    formatters_by_ft = {
      -- ...
    },
    formatters = {
      ['formatter-name'] = {
        prepend_args = { '--flag', 'value' },
      },
    },
  },
}

Adding a Linter

1. Add to Mason Tool Installer

In lua/plugins/lsp.lua, add linter to ensure_installed:

{
  'WhoIsSethDaniel/mason-tool-installer.nvim',
  opts = {
    ensure_installed = {
      -- ... existing tools
      'new-linter',
    },
  },
}

2. Configure in nvim-lint

In lua/plugins/format.lua, add to linters_by_ft:

config = function()
  local lint = require('lint')

  lint.linters_by_ft = {
    -- ... existing linters
    newlang = { 'linter-name' },
  }

  -- Rest of config...
end

3. Customize Linter (Optional)

Add custom args:

lint.linters.yamllint.args = {
  '-d',
  '{extends: default, rules: {line-length: {max: 120}}}',
  '-f',
  'parsable',
  '-',
}

Formatters by Filetype

Current configuration:

Filetype	Formatter	Mason Package
lua	stylua	stylua
python	ruff_format	ruff
javascript, typescript	prettier	prettier
javascriptreact, typescriptreact	prettier	prettier
css, scss, less	prettier	prettier
html	prettier	prettier
json, jsonc	prettier	prettier
yaml	prettier	prettier
markdown	prettier	prettier
bash, sh	shfmt	shfmt
fish	fish_indent	Built-in
toml	taplo	taplo
_ (all)	trim_whitespace	Built-in

Linters by Filetype

Current configuration:

Filetype	Linter	Mason Package
lua	selene	N/A (install separately)
bash, sh	shellcheck	shellcheck
markdown	markdownlint	markdownlint
yaml	yamllint	yamllint

Multiple Formatters

Run formatters in sequence:

formatters_by_ft = {
  python = { 'isort', 'black' },  -- Run isort, then black
}

Or specify alternatives (first available):

formatters_by_ft = {
  javascript = { 'prettierd', 'prettier' },  -- Try prettierd, fallback to prettier
}

Common Formatters

Language	Formatter	Mason Package	Notes
Lua	stylua	stylua	Config in .stylua.toml
Python	ruff_format	ruff	Fast, Rust-based
Python	black	black	Popular alternative
JavaScript/TypeScript	prettier	prettier	Universal JS formatter
JavaScript/TypeScript	prettierd	prettierd	Daemon (faster)
Bash/Shell	shfmt	shfmt	Shell script formatter
Rust	rustfmt	Built-in	Via rustup
Go	gofmt/goimports	Built-in	Via go toolchain
C/C++	clang-format	clang-format	Style configuration
JSON	prettier	prettier	Or jq
YAML	prettier	prettier	Or yamlfmt
TOML	taplo	taplo	TOML formatter
Markdown	prettier	prettier	Or markdownlint
HTML/CSS	prettier	prettier	Universal web formatter

Common Linters

Language	Linter	Mason Package	Notes
Lua	selene	N/A	Install separately
Python	ruff	ruff	Fast, replaces flake8
Python	pylint	pylint	Comprehensive
JavaScript/TypeScript	eslint	eslint-lsp	Via LSP (preferred)
Bash/Shell	shellcheck	shellcheck	Shell script linter
YAML	yamllint	yamllint	YAML linter
Markdown	markdownlint	markdownlint	Markdown linter
JSON	jsonlint	jsonlint	JSON linter

Formatter Options

Prepend Args

Add arguments before default args:

formatters = {
  shfmt = {
    prepend_args = { '-i', '2', '-ci' },  -- 2-space indent, case indent
  },
}

Replace Command

Override the command:

formatters = {
  prettier = {
    command = 'prettierd',
  },
}

Set Stdin

Control stdin behavior:

formatters = {
  myformatter = {
    stdin = false,  -- Don't use stdin
  },
}

Linter Triggers

Linters run on these events:

• BufWritePost - After saving file
• InsertLeave - When leaving insert mode
• BufEnter - When entering buffer

Manual Commands

• :ConformInfo - Show formatter info for current buffer
• :lua require('lint').try_lint() - Run linter manually
• <leader>cf - Format current buffer (keymap)

Examples

Add Rust Formatter

-- 1. No Mason package needed (rustfmt via rustup)

-- 2. Add to conform.nvim
formatters_by_ft = {
  rust = { 'rustfmt' },
}

Add ESLint (via LSP)

ESLint is configured as LSP in lua/plugins/lsp.lua, not nvim-lint:

vim.lsp.config.eslint = {
  cmd = { 'vscode-eslint-language-server', '--stdio' },
  filetypes = { 'javascript', 'typescript', ... },
  -- ...
}

Add Black (Python)

-- 1. Add to mason-tool-installer
ensure_installed = {
  'black',
}

-- 2. Add to conform.nvim
formatters_by_ft = {
  python = { 'black' },  -- Or: { 'isort', 'black' }
}

Add Gofmt (Go)

-- No Mason package needed (via go toolchain)

formatters_by_ft = {
  go = { 'gofmt' },  -- Or: 'goimports'
}

Customize Prettier

formatters = {
  prettier = {
    prepend_args = { '--single-quote', '--trailing-comma', 'all' },
  },
}

Workflow

1. Identify formatter/linter for the language
2. Add tool to mason-tool-installer in lsp.lua
3. Add filetype mapping to conform/nvim-lint in format.lua
4. Customize args if needed
5. Run :MasonToolsInstall to install
6. Test with :ConformInfo or by formatting
7. Run make lint and make format to validate config

Notes

• Formatters run via <leader>cf keymap
• Linters run automatically on save and insert leave
• Some formatters are built-in (fish_indent, gofmt)
• Some linters run via LSP (eslint) instead of nvim-lint
• Check Mason for available packages: :Mason
• Use LSP for linting when possible (better integration)