//@ `SomethingOrNothing<i32>` to get back our `NumberOrNothing`.
type NumberOrNothing = SomethingOrNothing<i32>;
//@ However, we can also write `SomethingOrNothing<bool>` or even `SomethingOrNothing<SomethingOrNothing<i32>>`.
//@ `SomethingOrNothing<i32>` to get back our `NumberOrNothing`.
type NumberOrNothing = SomethingOrNothing<i32>;
//@ However, we can also write `SomethingOrNothing<bool>` or even `SomethingOrNothing<SomethingOrNothing<i32>>`.
// ## Generic `impl`, Static functions
//@ The types are so similar, that we can provide a generic function to construct a `SomethingOrNothing<T>`
// ## Generic `impl`, Static functions
//@ The types are so similar, that we can provide a generic function to construct a `SomethingOrNothing<T>`
//@ `vec_min`? Of course, we can't take the minimum of a vector of *any* type. It has to be a type
//@ supporting a `min` operation. Rust calls such properties that we may demand of types *traits*.
//@ `vec_min`? Of course, we can't take the minimum of a vector of *any* type. It has to be a type
//@ supporting a `min` operation. Rust calls such properties that we may demand of types *traits*.
//@ For now, just ignore the `Copy`, we will come back to this point later.
//@ A `trait` is a lot like interfaces in Java: You define a bunch of functions
//@ you want to have implemented, and their argument and return types. <br/>
//@ For now, just ignore the `Copy`, we will come back to this point later.
//@ A `trait` is a lot like interfaces in Java: You define a bunch of functions
//@ you want to have implemented, and their argument and return types. <br/>
//@ first argument the special `self` argument. I could, alternatively, have
//@ made `min` a static function as follows: `fn min(a: Self, b: Self) -> Self`.
//@ first argument the special `self` argument. I could, alternatively, have
//@ made `min` a static function as follows: `fn min(a: Self, b: Self) -> Self`.
pub trait Minimum : Copy {
fn min(self, b: Self) -> Self;
}
pub trait Minimum : Copy {
fn min(self, b: Self) -> Self;
}
//@ Before going on, take a moment to ponder the flexibility of Rust's take on abstraction:
//@ We just defined our own, custom trait (interface), and then implemented that trait
//@ *for an existing type*. With the hierarchical approach of, e.g., C++ or Java,
//@ Before going on, take a moment to ponder the flexibility of Rust's take on abstraction:
//@ We just defined our own, custom trait (interface), and then implemented that trait
//@ *for an existing type*. With the hierarchical approach of, e.g., C++ or Java,
//@
//@ In case you are worried about performance, note that Rust performs *monomorphisation*
//@ of generic functions: When you call `vec_min` with `T` being `i32`, Rust essentially goes
//@
//@ In case you are worried about performance, note that Rust performs *monomorphisation*
//@ of generic functions: When you call `vec_min` with `T` being `i32`, Rust essentially goes