Flattening Rust’s learning curve

It's like reading "A Discipline of Programming", by Dijkstra. That morality play approach was needed back then, because nobody knew how to think about this stuff.

Most explanations of ownership in Rust are far too wordy. See [1]. The core concepts are mostly there, but hidden under all the examples.

    - Each data object in Rust has exactly one owner.
      - Ownership can be transferred in ways that preserve the one-owner rule.
      - If you need multiple ownership, the real owner has to be a reference-counted cell. 
        Those cells can be cloned (duplicated.)
      - If the owner goes away, so do the things it owns.

    - You can borrow access to a data object using a reference. 
      - There's a big distinction between owning and referencing.
      - References can be passed around and stored, but cannot outlive the object.
        (That would be a "dangling pointer" error).
      - This is strictly enforced at compile time by the borrow checker.

That explains the model. Once that's understood, all the details can be tied back to those rules.

[1] https://doc.rust-lang.org/book/ch04-01-what-is-ownership.htm...

In my experience, understanding the rules of the borrow checker is not enough to be able to write rust code in practice. For example, ~6 months into using rust I was stumped trying to move data out of a mutable reference. Trying to do this directly by dereferencing gives compiler errors like "cannot move out of `*the_ref` which is behind a mutable reference". If you know rust, you're probably either yelling "you idiot! you can't move out of mutable references!" or "you idiot! just use std::mem::take!" (the latter of course being the right way to do this) but that's not obvious from the borrow checker rules.

My experience learning rust has been like a death by 1000 cuts, where there's so many small, simple problems that you just have to run into in the wild in order to understand. There's no simple set of rules that can prepare you for all of these situations.