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...

The second bullet in the second section is overpromising badly. In fact there are many, many, many ways to write verifiably correct code that leaves no dangling pointers yet won't compile with rustc.

Frankly most of the complexity you're complaining about stems from attempts to specify exactly what magic the borrow checker can prove correct and which incantations it can't.

A great teaching technique I learned from a very good match teacher is that when explaining core concepts, the simplified definitions don't need to be completely right. They are much simpler to grasp and adding exceptions to these is also quite easy compared to trying to understand correct, but complex, definitions at the beginning.

Yeah, but the whole purpose here is "flattening the learning curve", and telling people code will work when it won't is doing the opposite.

That bullet, at its most charitable, defines the "idealized goal" of the borrow collector. The actual device is much less capable (as it must be, as the goal is formally undecidable!), and "learning rust" requires understanding how.

Ironically, most people understand "learning curves" counterintuitively.

If a "learning curve" is a simple X-Y graph with "time" and "knowledge" being on each axis respectively, then what sort of learning curve is preferable: a flatter one or a steep one?

Clearly, if you graph large increases of knowledge over shorter periods of time, a steeper learning curve is more preferable. "Flattening the learning curve" makes it worse!

But for some reason, people always reverse this meaning, and so the common idiom breaks down for people who try to reason it out.