[etyp]

Safe programs extend beyond those that Rust's borrow checker accepts though. There is more than one way to make a program safe, not all of them would be valid Rust.

[goku12]

There are more than one way to achieve safety in Rust. Two more, infact - runtime safety and fully manual (unsafe with some additional work). Runtime safety is a very fast way to overcome the resistance offered by the borrow checker. While it does slowdown the code a little bit, that should be pretty fine for prototyping. A more careful use of runtime checks will still give you a program more performant than in most other languages.

[dzaima]

Runtime safety still comes with a good amount of complication source-wise, having to spam RefCell/Arc everywhere, and whatever derefs/.get()s they necessitate, and probably a different approach to passing references. Refactoring either that or unsafe away after being done with prototyping isn't trivial, if even possible without entirely rethinking the approach.