For folks curious about the supported language subset, here's a summary:

- Modules aren't implemented yet, but are high on the list

- Continuation-based control flow isn't supported yet, including break and promises. Tail calls are supported though.

- No support for complex numbers, bignums, weak hashtables, immutable hashtables, prefab structs, regexp, or file I/O support

Most of the rest of racket/base should work, according to the README. There's also a FFI for javascript, including bindings for Math, DOM, Canvas, MathJax, XTermJS, and JSXGraph. Overall feels like you can use most of the language right now unless you need odd Racket-isms or call/cc.