vim-rescript

Vim runtime files for ReScript.

If you are experiencing any troubles, open an issue or visit our Forum and ask for guidance.

Features

• Syntax highlighting for ReSript files
• Filetype detection for .res, .resi
• Basic automatic indentation

See :h rescript for the detailed helpfile.

Installation

vim-rescript can be installed either manually or by using your favourite plugin manager.

" vim-plug
Plug 'rescript-lang/vim-rescript'

" Vundle
Plugin 'rescript-lang/vim-rescript'

" NeoBundle
NeoBundle 'rescript-lang/vim-rescript'

-- vim.pack builtin, require neovim 0.12+
vim.pack.add { 'https://github.com/rescript-lang/vim-rescript' }

-- Lazy.nvim
{ 'rescript-lang/vim-rescript', ft = 'rescript' }

You can also pin your installation to specific tags (check our releases here):

With Plug:

Plug 'rescript-lang/vim-rescript', {'tag': 'v3.0.0'}

With Lazy.nvim:

{ 'rescript-lang/vim-rescript', tag = "v3.0.0" }

Setup LSP

First you need install the language server for ReScript from npm

Note If you are using mason.nvim you can install the ReScript Language Server using the command MasonInstall rescript-language-server

Or intall using npm:

npm install -g @rescript/language-server

The binary is called rescript-language-server

Neovim LSP builtin

Install the nvim-lspconfig package and setup the LSP

vim.lsp.config("rescriptls", {})
vim.lsp.enable("rescriptls")

For more details, see server configuration

COC (Vim or Neovim)

(:h rescript-coc)

After the installation, open your coc config (:CocConfig) and add the following configuration:

"languageserver": {
  "rescript": {
    "enable": true,
    "module": "rescript-language-server",
    "args": ["--node-ipc"],
    "filetypes": ["rescript"],
    "rootPatterns": ["rescript.json", "bsconfig.json"]
  }
}

Tree Sitter

Tree-sitter is a parser generator tool and incremental parsing library. Unlike regex-based syntax highlighting, Tree-sitter builds a full concrete syntax tree for a source file and updates it incrementally as you type. In Neovim, this enables more accurate, context-aware highlighting, smarter text objects, and structural navigation — none of which are possible with pattern matching alone.

Syntax Highlighting Mechanisms in Neovim

Neovim supports three distinct highlighting mechanisms that can be used independently or layered on top of each other:

1. Regex-based syntax (:h syntax) — The classic Vim approach. Syntax rules are defined as regex patterns in .vim files. This is what vim-rescript provides by default and works in both Vim and Neovim without any additional dependencies.

2. Tree-sitter (:h treesitter) — Available since Neovim 0.5. Uses a parsed AST instead of regex patterns, producing more precise and context-aware highlighting. Requires a compiled parser for each language. This plugin ships Tree-sitter highlight queries in the queries/rescript/ directory, which Neovim loads automatically once a ReScript parser is installed.

3. LSP semantic tokens (:h lsp-semantic_tokens) — Available since Neovim 0.9. The language server sends token data with semantic information about each symbol (e.g. distinguishing a local variable from a type alias or a module name). These are applied on top of Tree-sitter or regex highlights and provide the highest level of semantic accuracy.

When all three are active, they layer in that order: regex forms the base, Tree-sitter overrides it with structural context, and LSP semantic tokens refine it further with type information from the compiler.

Installing the ReScript Parser

Neovim does not ship a ReScript parser. You need to install one separately.

nvim-treesitter is archived, meaning it no longer receives updates, but it still works and remains the most common way to install and manage parsers. Install it as a regular plugin.

Now, overwrite the parser config information to install the latest version of parser.

---@type ParserInfo
local rescript_parser = {
  install_info = {
    revision = 'v6.0.0',
    url = 'https://github.com/rescript-lang/tree-sitter-rescript',
    queries = 'queries/'
  },
}

vim.api.nvim_create_autocmd('User', {
  pattern = 'TSUpdate',
  callback = function()
    require('nvim-treesitter.parsers').rescript = rescript_parser
  end,
})

require('nvim-treesitter.parsers').rescript = rescript_parser

Now, open nvim and install using the command TSInstall rescript. Once a parser is installed, Neovim loads the Tree-sitter queries from this plugin automatically when you open a .res or .resi file.

Credits

• amirales: Started the plugin w/ syntax & indent functionality