This is a really interesting project and I like where you're taking it. I've played with Nim for a number of years, and I really like the no-runtime aspect of Muon and the flexibility and simplicity that you've created with it. Unlike many others in this thread, I like the whitespace decisions you've made, though I go in the opposite direction - have you thought about making braces optional?
Your roadmap looks great as well. Have you considered any of the following?:
- Lisp-style Macros (e.g. Macros as functions that transform an AST object) -- this would also answer many of the preprocessor questions you had, especially if you can specify compile-time behavior (like in zig)
- Github-based decentralized package management system
- Owned pointers memory management options