I noticed an offhand tweet from Phil Tomson about Codio adding OPAM support, and naturally had to take a quick look. I was really impressed by the whole process, and ended up building the Mirage Xen website unikernel directly from my web browser in less than a minute, including registration!

• I signed up to Codio for free (since it’s a public project) using GitHub oAuth (only public identity access required at first, no repository access).
• Selected a git project and pointed it at the mirage-www repository.
• At this point, you get the usual file explorer and code editor view in your browser. The magic begins when you go to “Tools/Terminal”, and an interactive Ubuntu shell pops up. Since Codio added opam support, setting up the Mirage environment is a breeze:

I notice Codio supports OCaml and opam on the server side now. — phil tomson (@philtor) March 26, 2014

$ parts install opam
$ opam init -a
$ eval `opam config env`
$ opam install mirage-www -y
$ make MODE=xen

Then have a cup of coffee while the box builds, and you have a mir-www.xen, all from your web browser! Codio has a number of deployment options available too, so you should be able to hook up a Git-based workflow using some combination of Travis or other CI service.

This is the first time I’ve ever been impressed by an online editor, and might consider moving away from my beloved vi...