Goodies for RacketScript

big-bang, javascript, web, compiler, programming-language, racket



Build Status

RacketScript is an experimental lightweight Racket to JavaScript compiler. The generated code is ES6, which can be translated to ES5 using Babel or Traceur. RacketScript aims to leverage both JavaScript and Racket's ecosystem, and make interoperability between them clean and smooth.

RacketScript takes in Racket source files, uses Racket's macro expander to produce Fully Expanded Programs, and then compile these fully expanded programs to JavaScript. RacketScript doesn't support Racket features which are expensive, for example proper tail calls and continuations.

Try RacketScript

You can try RacketScript in your browser at RacketScript Playground.


Following system packages are required -

  • Racket 6.4 or higher
  • NodeJS (4.0 or higher) and NPM
  • Make

NPM and Racket package installation steps could be done by directly by executing make setup or raco pkg install at RacketScript root directory.

RacketScript will generate Gulpfiles to compile ES6 to ES5 using Traceur or Babel. If you wish to run ES6 modules directly, install Traceur using NPM. Babel is recommended for writing NodeJS programs.

If you wish to hack on RacketScript code or run tests, lints and coverage tool, run make setup-extra form RacketScript root directory. See Makefile for more information. This will also install js-beautify which produces beautified JavaScript output.

If you do not wish to pollute your root NPM directory, you can set a custom global location by changing your npmrc (eg. echo "prefix = $HOME/.npm-packages" >> ~/.npmrc. Then add /prefix/path/above/bin to your PATH.


The compiler is written in Typed Racket. To avoid long startups, it is advised to pre-compile Racket sources to bytecode. This step is not required if are not making any changes to compiler.

# From source root
$ make build

Basic Usage

RacketScript compiler is named racks.

$ racks -h # show help

To compile a Racket source file:

# Installs all NPM dependencies and compile file.rkt
$ racks /path/to/file.rkt

The above command will create a output build directory named js-build, copy RacketScript runtime, copy other support files, install NPM dependencies, compile file.rkt and its dependencies.

The compiled ES6 modules typically goto one of following three folders:

  • "modules": The normal Racket files.
  • "collects": Racket collects source files.
  • "links": Other third party packages.
  • "dist": Contains sources compiled to ES6 or bundled JavaScript ready for distribution.

Here are few other examples that would come in handy:

# To skip `npm install` step. Useful when building
# for second time.
$ racks -n /path/to/source.rkt

# To beautify assembled modules use `-b`. Make sure
# `js-beautify` is installed from NPM or your
# package manager.
$ racks -b /path/to/source.rkt

# Override default output directory
$ racks -d /path/to/output/dir /path/to/source.rkt

# Print JavaScript output to stdout
$ racks --js --js-beautify /path/to/source.rkt

By default tail call optimization is turned off. To enable translation of self recursive tail calls to loop, pass --enable-self-tail flag.

$ racks --enable-self-tail /path/to/source.rkt


By default RacketScript will use Traceur and produce dist/compiled.js. To execute inside NodeJS, execute bootstrap.js in output directory. For running in browser, include the Traceur runtime along with dist/compiled.js.

A more robust (and less portable) way, is to run the ES6 modules generated in modules directly from Traceur. Goto modules output directory and execute $ traceur /path/to/source.js.


RacketScript could also use Babel. It will compile each assembled ES6 module to ES5, and put it in dist directory, persevering original directory structure. Replace above command with following -

# Use `--target` or `-t` flag.
$ racks --target babel /path/to/source.rkt

This will compile each ES6 module generated by RacketScript, and put in dist with same directory structure.

Running Tests and Coverage

# Install build and test dependencies:
$ make setup-extra

# Run unit tests
$ make unit-tests

# Run integration tests
$ make integration-test

# Run all tests
$ make test

To test Racket output against JavaScript output of specific Racket source file(s), use fixtures.rkt. Run ./fixtures.rkt -h inside $RACKETSCRIPT/tests directory to see basic usage.

For running coverage:

$ make coverage # Consider coverage of all tests
$ make coverage-unit-test # Just consider unit-test coverage

Look in the Makefile for more targets.

Related Work