I've only skimmed through the docs so far, and it sounds interesting, but..

> The Mojo standard library, compiler, and runtime are not available for local development yet, so we created a hosted development environment where you can try it out. We call it the Mojo Playground!

Is this going to be a SaaS-style programming language, or will it be open source and local later? I'm not sure I understand why a new programming language wouldn't start off as open source, or at least able to be used locally?