Please don't mind my possibly simplistic question — but is this something that would bring Rust development closer to a Lisp environment? Seems like an interesting project.
This is more in line with building a REPL for your own language.
Lisp environments are just that; environments. That is to say that there is a runtime that holds your code in memory, which then enables a REPL to replace parts of the code in memory while the program is running.
This implies an interpreted language (that might or might not also be compiled further at runtime), which Rust is not. It also heavily implies a garbage collector, which Rust doesn't have. Lastly, type guarantees in these languages tend to be less strong as the system almost by definition is already very dynamic.
