You have a point. We might actually end up with a multitude of lazy types (akin to `RefCell` vs. `Mutex` in Rust). In high-level languages like ML and Haskell,

You have a point. We might actually end up with a multitude of lazy types (akin to `RefCell` vs. `Mutex` in Rust). In high-level languages like ML and Haskell, forcing all lazy data to be boxed, and atomically mutating pointers to boxed data, seems like a reasonable solution.