It's an interesting take on an IR. It's goal is to support the current C/C++/JS backend but also to make generating native assembly easy to do as well.

It also doesn't rely on lexical scopes to do analysis for things like lifetimes, nil tracking, destructors, etc. Instead it uses the versioned variables AFICT to enable those features more directly. Should be much simpler for the compiler implementation for 99% of cases versus traditional SSA blocks.

Unfortunately I'm busy writing Nim code and not able to play with the new Nimony compiler framework. I'm excited about incremental compilation and borrow checking features though.