This is a web playground for the Have programming language. See it running on http://havelang.org/playground/.
This project was possible thanks to GopherJS, and it is actually based on the GopherJS playground.
To update the entire playground environment, just run go generate github.com/vrok/have-playground. It will install your local version of GopherJS compiler, build the playground, make a temporary copy of Go to /tmp/gopherjsplayground_goroot, rebuild and copy the standard library into the pkg directory.
Working on the playground application itself is made easier by using the gopherjs serve command to rebuild and serve the playground every time you refresh the browser.
gopherjs serveThen open http://localhost:8080/github.com/vrok/have-playground.