Rust looks very interesting... I have something like this:
pub fn new<S: Into < String > >(first_name: S, last_name: S, age: u8, university: Option < String > ) -> Person
...
why is it not working if I change it to "university: Option< S >"?
It will convert String (not really) or &str on other parameters. Is it possible to change "where" in a way to do the same thing for Option? Thx!
Using an Option<S> is perfectly valid given only the info we've been given.
Technically you could say where Option<S>: Into<String> but that most likely isn't what you want to do.
Please share some more code to elaborate the errors your code presents.
What I would like to get is that I can send Option < &str > or Option < String > into a function parameter... (Option < Something > where < who knows > 
)
I can send &str or String to the same function parameter when I add "where S: Into < String > ".
What I would like to do is the same thing for Option<&str> and Option < String >.
I can define that parameter as Option < String > but then I have to convert from &str to String every time I call that function with a &str --- Some("something".to_string());
For example this is not working:
fn test< S>(str: Option< S>) where
S: Into< String> {
println!("test {}", str.into());
}
fn main() {
test(Some("something"));
test(Some("something".to_string()));
}
You have to "remove" the Option layer first using unwrap or match or if let,...
For example:
println!("test {}", str.unwrap().into());
omg... Thx! 
Instead of being generic over <S : Into<String>> and then using S in the signature, you can also use impl Into<String> wherever S was used, which will implicitly declare as many generic parameters as there are occurrences of S. This has the advantage of, in your example, allowing to have first_name: &str and last_name: String.
Thank you, Yandros. Much appreciated.
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