ReScript grammar for Tree-sitter

This repository contains a parser definition of the ReScript language for the Tree-sitter parser generator tool.

Athough Tree-sitter has many applications, the main intent of this parser is powering the nvim-treesitter-rescript NeoVim plugin which may be used to improve development experience in the NeoVim + ReScript combo.

Queries for text objects are also included which help you to navigate, select, and modify ReScript code syntactically. For NeoVim, the nvim-treesitter-textobjects plugin is required to use Tree-sitter text objects.

Installation

Neovim

If you want ReScript Tree-sitter in NeoVim, you will first need to register a new parser for it like so:

local parser_config = require("nvim-treesitter.parsers").get_parser_configs()
parser_config.rescript = {
  install_info = {
    url = "https://github.com/nkrkv/tree-sitter-rescript",
    branch = "main",
    files = { "src/scanner.c" },
    generate_requires_npm = false,
    requires_generate_from_grammar = true,
    use_makefile = true, -- macOS specific instruction
  },
}

This will make TSInstall rescript globally available. For more persistent approach you should add this parser to your Lua configuration.

Default configuration detects .res and .resi files. You can confirm that it's correctly installed by using nvim-treesitter/playground and invoking TSPlaygroundToggle when you are in the ReScript file.

• Notice that by default you will not see the highlighting! To enable highlighting, you will need to install this package either as a dependency or directly.

If you are using lazy.nvim example configuration will look like so:

  {
    "nvim-treesitter/nvim-treesitter",
    dependencies = {
      "nkrkv/tree-sitter-rescript"
    },
    opts = function(_, opts) -- this is needed so you won't override your default nvim-treesitter configuration
      vim.list_extend(opts.ensure_installed, {
        "rescript",
      })

      local parser_config = require("nvim-treesitter.parsers").get_parser_configs()
      parser_config.rescript = {
        install_info = {
          url = "https://github.com/nkrkv/tree-sitter-rescript",
          branch = "main",
          files = { "src/scanner.c" },
          generate_requires_npm = false,
          requires_generate_from_grammar = true,
          use_makefile = true, -- macOS specific instruction
        },
      }
    end,
  }

• Legacy way of installing the parser is available via nvim-treesitter-rescript
• If you want it for other purposes, you probably know what to do.

Contributing

Contributions are welcome. Here’s how you can help:

🙂 Provide a minimal ReScript snippet which produces an (ERROR) node or otherwise incorrect syntax tree. Open a new issue providing this snippet and the resulting syntax tree. You can use the following command to see the syntax tree:

yarn tree-sitter parse /path/to/your/snippet.res

🤩 Add a failing test case for a snippet which is valid ReScript but produces an incorrect syntax tree. Fix the grammar.js. Make sure nothing is broken: make test test_wild shows 100% test success. Open a pull request.