If you could write an OS from scratch...

Okay, so most every OS out there is C-based.  If you could magically write a complete hardware-controlling OS all the way up to the UI and applications using a different language, which would you choose?

Though I like Lisp, I think I'd have to choose Erlang, maybe NewSqueak for embedded/smaller systems.

I'd study and follow the concept of a Lisp Machine, providing an OS that will be mostly written in a high-level dynamic language which you can stop, modify and understand anytime.

Just like Dennis Ritchie created his own programming language to write UNIX, I'd create my own programming language to create a more dynamic operating system.

My language would be based on Python, but contain no stupid statements, some quirks removed, tail-call elimination, functional parameters, and a new virtual machine which would have to be faster, GIL-less, and able to save state and reload them like many Lisps.

The OS would be clearly divided in four parts:
1. The kernel and core, which can load the hardware drivers.
2. The high-level API, resource broker, services and artificial intelligence services.
3. The globally unified virtual filesystem, made up from plugins that will allow you to mount absolutely anything and mount on-the-fly based on functional directories, URI parameters and everything I can possibly think of.
4. The API compatibility layer, which would include a POSIX API and a port of Wine.
5. The core applications, which would include the GNU system and a grammar-based editor which can serve as a text editor and a specialized editor for any kind of text or binary file provided with a grammar.

I wouldn't dare to write a GUI at first; I'd settle for applications using any number of full-screen graphical consoles (which would be far more capable than a UNIX terminal; think something like Windows console, only gone right), full-screen framebuffers and a full-screen OpenGL context.