Incorrect: collecting to a Result stops on the first error, as documented explicitly in https://doc.rust-lang.org/std/result/enum.Result.html#method....

Map and friends are lazy, so the whole chain is run once and in full for each item. Collect will short circuit at the first Err encountered. You can even try it out by using `.inspect()` in the chain to see that the iterations don't go past the first error.

Collecting into a result will short circuit.

That's not true: https://play.rust-lang.org/?version=stable&mode=debug&editio...

    let v: Option<Vec<i32>> = (0..5).map(|i| {
        print!("{i} ");
        if i == 3 { None } else { Some(i) }
    }).collect();
    // prints 0 1 2 3

Short-circuit refers to stopping not skipping.

I don’t understand. The example you replied to stopped, not skipped.

that should print 4 and 5 if that was skipping ?

Yeah I read too fast.

One of the issues with type inference, this exact same code does different things depending on whether the result is assigned to `Option<Vec<i32>>` or `Vec<Option<i32>>`

Except it does! https://doc.rust-lang.org/src/core/result.rs.html#2029

Realistically, the 'problem' is that many programmers today get scared away when you start mentioning monads or effect systems. Realistically though, the solution is to have first class monads or effect systems in rust and other languages. A lot of language design today is 'wasted' in the sense that we spend time implementing special cases (Promises in javascript, ? syntax in rust, async syntax in rust) without any thought given to the meta problem. In my opinion, the lack of attention to the meta problem is due to programmers being scared of such topics.