tree-sitter-dune

March 20, 2026 · View on GitHub

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Tree-sitter grammar for Dune build system files.

Features

  • Complete dune file support: Parses all major stanzas including executable, library, rule, test, alias, and more
  • dune-project support: Full support for project metadata files including lang, name, version, package, and all project configuration stanzas
  • dune-workspace support: Complete support for workspace configuration including context, profile, and cross-compilation setup
  • Syntax highlighting: Comprehensive highlight queries for editor integration
  • Field markers: Structured AST with named fields for precise code navigation
  • 86+ test cases: Extensively tested against real-world Dune files

Supported File Types

  • dune - Build files in each directory
  • dune-project - Project metadata and configuration
  • dune-workspace - Workspace-level settings and build contexts

Installation

NPM

npm install tree-sitter-dune

Cargo

cargo add tree-sitter-dune

Tree-sitter CLI

git clone https://github.com/tmcgilchrist/tree-sitter-dune
cd tree-sitter-dune
tree-sitter generate
tree-sitter test

Usage

Node.js

const Parser = require('tree-sitter');
const Dune = require('tree-sitter-dune');

const parser = new Parser();
parser.setLanguage(Dune);

const sourceCode = `
(library
 (name my_lib)
 (libraries base stdio))
`;

const tree = parser.parse(sourceCode);
console.log(tree.rootNode.toString());

Rust

use tree_sitter::Parser;

fn main() {
    let mut parser = Parser::new();
    parser.set_language(&tree_sitter_dune::LANGUAGE.into()).expect("Error loading Dune grammar");

    let source_code = r#"
(library
 (name my_lib)
 (libraries base stdio))
"#;

    let tree = parser.parse(source_code, None).unwrap();
    println!("{}", tree.root_node().to_sexp());
}

Python

from tree_sitter import Language, Parser
import tree_sitter_dune

parser = Parser()
parser.set_language(Language(tree_sitter_dune.language(), "dune"))

source_code = b"""
(library
 (name my_lib)
 (libraries base stdio))
"""

tree = parser.parse(source_code)
print(tree.root_node.sexp())

Go

package main

import (
    "context"
    "fmt"
    sitter "github.com/tree-sitter/go-tree-sitter"
    dune "github.com/tmcgilchrist/tree-sitter-dune/bindings/go"
)

func main() {
    parser := sitter.NewParser()
    parser.SetLanguage(sitter.NewLanguage(dune.Language()))

    sourceCode := []byte(`
(library
 (name my_lib)
 (libraries base stdio))
`)

    tree := parser.Parse(sourceCode, nil)
    fmt.Println(tree.RootNode().ToSexp())
}

Editor Integration

Neovim

With nvim-treesitter:

require'nvim-treesitter.configs'.setup {
  ensure_installed = { "dune" },
  highlight = {
    enable = true,
  },
}

Emacs

neocaml provides neocaml-dune-mode, a tree-sitter based major mode for dune, dune-project, and dune-workspace files. It uses Emacs's built-in treesit library (Emacs 29+).

Grammar Coverage

dune files

✅ Fully Supported:

  • executable, executables - Build executables
  • library - OCaml libraries
  • test, tests - Test executables
  • rule - Custom build rules with actions
  • alias - Named build targets
  • install - Installation rules
  • toplevel - Custom toplevels
  • copy_files - File copying with globs
  • include - Include dune fragments
  • menhir - Menhir parser generator
  • ocamllex, ocamlyacc - Lexer/parser generation
  • foreign_library - C/C++ libraries
  • plugin - Compiler plugins
  • mdx - Markdown executable blocks
  • coq.theory - Coq integration
  • cram - Cram tests
  • subdir - Nested directories
  • env - Environment configuration
  • ignored_subdirs - Ignore directories
  • deprecated_library_name - Library renaming
  • Actions: run, bash, copy, diff, write-file, with-stdout-to, progn, and 15+ more

Coverage: 30/34 stanzas (88%), ~99% real-world usage

dune-project files

✅ Fully Supported (100% coverage):

  • lang - Language version (required)
  • name, version, license - Project metadata
  • authors, maintainers, maintenance_intent - Contributors
  • homepage, documentation, bug_reports - URLs
  • source - Repository information (github/git/uri)
  • package - Package definitions with complex dependencies
  • generate_opam_files, opam_file_location - OPAM integration
  • using - Extension configuration (menhir, coq, etc.)
  • formatting - Formatter settings
  • dialect - Custom dialects
  • pin - Pin dependencies
  • warnings - Compiler warnings config
  • explicit_js_mode - JavaScript mode
  • subst - Watermarking
  • Boolean flags: accept_alternative_dune_file_name, executables_implicit_empty_intf, expand_aliases_in_sandbox, implicit_transitive_deps, map_workspace_root, use_standard_c_and_cxx_flags, wrapped_executables

Coverage: 29/29 stanzas (100%)

dune-workspace files

✅ Fully Supported:

  • context - Build contexts
    • (context default) - Default context
    • (context (opam ...)) - Opam switch contexts
    • Fields: switch, name, profile, toolchain, host, target
    • Flags: merlin, generate_merlin_rules, disable_dynamically_linked_foreign_archives
    • Additional: root, lock_dir, paths, env, fdo, targets
  • profile - Build profile selection (dev/release/custom)

Development

Building

npm install -g tree-sitter-cli
tree-sitter generate

Testing

tree-sitter test

Debugging

tree-sitter parse examples/dune
tree-sitter parse --debug examples/dune-project

Contributing

Contributions are welcome! Please:

  1. Add tests for any new features in test/corpus/
  2. Ensure all tests pass with tree-sitter test
  3. Update this README if adding new stanza support
  4. Follow the existing code style

Adding New Stanzas

  1. Define the stanza in grammar.js:

    _stanza_my_new_stanza: ($) =>
  dune_stanza(
    $,
    "my_stanza",
    choice(
      dune_field($, "field_name", $.value_type),
      $.sexp,
    ),
  ),

  2. Add it to the stanza choice list

  3. Create tests in test/corpus/

  4. Run tree-sitter generate && tree-sitter test

Resources

License

MIT