How to return Ok unit type of std::result<(), E>?

问题

If I define a function:

fn f() -> Result<(), E> {
    // How to return Ok()?
}

How can I return the Ok in std::result with the unit type ()?

回答1:

The only value of type () is (), so just put that inside the Ok constructor:

fn f() -> Result<(), E> {
    Ok(())
}

回答2:

Use Ok(()) as in

fn f() -> Result<(), E> {
    Ok(())
}

来源：https://stackoverflow.com/questions/27945858/how-to-return-ok-unit-type-of-stdresult-e