nvim/lua/plugins/treesitter.lua

-- since `vim.tbl_deep_extend`, can only merge tables and not lists, the code above
-- would overwrite `ensure_installed` with the new value.
-- If you'd rather extend the default config, use the code below instead:
return {
  {
    "nvim-treesitter/nvim-treesitter",
    opts = function(_, opts)
      vim.list_extend(opts.ensure_installed, {
        "rust",
      })
    end,
    config = function(_, opts)
      if type(opts.ensure_installed) == "table" then
        ---@type table<string, boolean>
        local added = {}
        opts.ensure_installed = vim.tbl_filter(function(lang)
          if added[lang] then
            return false
          end
          added[lang] = true
          return true
        end, opts.ensure_installed)
      end
      require("nvim-treesitter.configs").setup(opts)

      local parser_config = require("nvim-treesitter.parsers").get_parser_configs()

      parser_config.nu = {
        install_info = {
          url = "https://github.com/nushell/tree-sitter-nu",
          files = { "src/parser.c" },
          branch = "main",
        },
        filetype = "nu",
      }
    end,
  },
  {
    "nvim-treesitter/playground",
    dependencies = { "nvim-treesitter/nvim-treesitter" },
    cmd = "TSPlaygroundToggle",
  },
}