> How can you do "Errors as values" at a large scale without do-notation / monads?
You don't need monads for this. You just need the ability to encode your error in some term like `Either e a` and ability to eliminate those terms. In Rust for example that is the `Result` type and you use pattern matching to eliminate those terms.
That's merely syntax sugar. Haskell doesn't even have this sugar and so in a monad you have to bind explicitly, and it's fine. It's not a pyramid of doom.
