gistfile1.txt

// Option is a simple example of an enum
// that is generic, with a variant that doesn't
// use that generic type. (None)
enum Option<T> {
    Some(T),
    None,
}

// Two functions that take different types of `Option`s
fn with_option_string(input: Option<string>) {}
fn with_option_number(input: Option<number>) {}

fn main(numerator, denominator) {
    // What is the type of `none`? Right now it's
    // `Option<?>` because we can't refine it yet...
    let none = Option.None;
    // This would refine it to `Option<string>`
    with_option_string(none);
    // But should this work? `Option.None` is still
    // a valid value, but the refinement above would
    // cause a type error.
    with_option_number(none);
}