API Docs: option

[steveklabnik]

Part of #29329

http://doc.rust-lang.org/std/option/

[leoyvens]

In the as_mut and iter_mut examples, a match is used with a None => {} arm. if let would be more idiomatic.

[devonhollowood]

In the documentation for unwrap_or (and maybe for related methods like ok_or and or), it would be nice to make a note that the arguments to a function are always fully evaluated, meaning that

fn foo(opt: Option<Bar>) -> Bar {
    let bar = opt.unwrap_or(return Bar::new());
    bar.baz()
}

will always return Bar::new() instead of opt.unwrap().baz(), even if opt is Some(_). This seems like a pitfall otherwise.

[steveklabnik]

I am happy to mentor anyone who wants to tackle this issue.

[irfanhudda]

@steveklabnik I'd like to help on this.

[steveklabnik]

@irfanhudda awesome! Let me know if I can help you help us in any way :)