Can this just be done as a lambda that is immediately evaluated? It's just much more verbose.

    let x = (|| -> Result<i32, std::num::ParseIntError> {
         Ok("1".parse::<i32>()?
          + "2".parse::<i32>()?
          + "3".parse::<i32>()?)
    })();

I want that stabilized so bad but it's not been really moving forward.

One of the first things I tried in Rust a couple of years ago coming from Haskell. Unfortunately it's still not stabilized :(

Why does this need special syntax? Couldn't blocks do this if the expression returns a result in the end?

Now that is pretty cool.

Ah yes, do-notation.