Developer tools

This page contains installation instructions for various development tools that can help with Eclair development.


Right now there is support for Eclair in editors via editor-agnostic tools such as tree-sitter and LSP. Editor-specific plugins or installation instructions might not be available yet.

Missing instructions for your favorite editor? Please open an issue on Github or consider contributing!

Syntax highlighting

There’s a tree-sitter grammar available for Eclair that can be used for syntax highlighting if your editor supports it. It should work for any editor that supports syntax highlighting.


You can setup syntax highlighting in Neovim using the nvim-treesitter package. Run the following commands in your shell to add support for Eclair syntax highlighting:

$ git clone && cd tree-sitter-eclair
$ npm install
$ ./node_modules/tree-sitter-cli/tree-sitter generate
$ ./node_modules/tree-sitter-cli/tree-sitter test
# The directory might be different based on your package manager.
# Here we are assuming "packer":
$ mkdir -p ~/.local/share/nvim/site/pack/packer/start/nvim-treesitter/queries/eclair
$ cp queries/highlights.scm ~/.local/share/nvim/site/pack/packer/start/nvim-treesitter/queries/eclair/

Then, open Neovim and add the following code to your init.lua:

local parser_config = require "nvim-treesitter.parsers".get_parser_configs()
parser_config.eclair = {
  install_info = {
    -- Change directory to where you cloned the repo
    url = "/path/to/tree-sitter-eclair",
    files = {"src/parser.c"}

vim.cmd 'au BufNewFile,BufRead *.eclair set filetype=eclair'

Finally, switch to normal mode and run the following command:

:TSInstall eclair

Now you should have syntax highlighting for any file with the “.eclair” extension!

Language Server

Eclair provides a built-in LSP server via the lsp subcommand. Currently it supports the following features:

  1. Show compiler errors directly from your editor
  2. Return type information of a value
  3. Highlight uses of a variable (references)

The LSP can be started as follows:

$ export DATALOG_dir=/path/to/eclair/cbits/
$ eclair lsp

Note: For now, the environment variable $DATALOG_DIR needs to be set and point to the cbits/ directory of the eclair repository. This is only temporary until the compiler is bootstrapped (then the whole compiler will become a single binary).


The Eclair LSP can be setup using the nvim-lspconfig package. (The LSP is not available via Mason yet, so it has to be installed with manual code.)

local lsp_util = require("lspconfig.util")

require('lspconfig.configs').eclair = {
  default_config = {
    cmd = { 'eclair', 'lsp' },
    filetypes = { 'eclair' },
    root_dir = lsp_util.find_git_ancestor,
    single_file_support = true,

require('lspconfig').eclair.setup {}

-- NOTE: Also add keybindings for LSP functionality.
-- (See nvim-lspconfig docs.)

Then try to open a file with the “.eclair” extension and try typing some code. You should start to see live feedback from the compiler.

© 2021-2023 Luc Tielen