Guide: option<int> doesn't implement ToStr

[steveklabnik]

the part of the guide that shows ::<> doesn't work now, or so I hear. Making an issue to investigate later

[crumblingstatue]

Here is the relevant section:

In a similar fashion, both of these work:

let input_num = from_str::<Option<uint>>("5");
let input_num: Option<uint> = from_str("5");

According to my understanding, the guide is saying here that both of these work, and do the same thing, which is take a string slice, and return an Option<T>.

The first line however, doesn't return an Option<T>.

from_str parameterizes over T, and returns an Option<T>. from_str::<Option<uint>> would actually return Option<Option<uint>>, if it was implemented.

If we change the first line to, let input_num = from_str::<uint>("5");, it works, and seems to be the intended thing.

[steveklabnik]

Yup! #17366 is a PR fixing it in exactly that way. 😄

[aochagavia]

The PR has been merged, so this is no loger an issue

[alexcrichton]

Thanks!