pub fn vec_min<T: Minimum>(v: &Vec<T>) -> Option<&T> {
let mut min: Option<&T> = None;
for e in v {
- min = Some(match min { /*@*/
- None => e, /*@*/
- Some(n) => n.min(e) /*@*/
- }); /*@*/
+ min = Some(match min {
+ None => e,
+ Some(n) => n.min(e)
+ });
}
min
}
//@ Notice that the return type `Option<&T>` is technically (leaving the borrowing story aside) a
//@ pointer to a `T`, that could optionally be invalid. In other words, it's just like a pointer in
//@ C(++) or Java that can be `NULL`! However, thanks to `Option` being an `enum`, we cannot forget
-//@ to check the pointer for validity, avoiding the safety issues of C(++).<br/>
+//@ to check the pointer for validity, avoiding the safety issues of C(++). <br/>
//@ Also, if you are worried about wasting space, notice that Rust knows that `&T` can never be
//@ `NULL`, and hence optimizes `Option<&T>` to be no larger than `&T`. The `None` case is represented
//@ as `NULL`. This is another great example of a zero-cost abstraction: `Option<&T>` is exactly like
// **Exercise 07.1**: For our `vec_min` to be usable with `BigInt`, you will have to provide an implementation of
// `Minimum`. You should be able to pretty much copy the code you wrote for exercise 06.1. You should *not*
-// make any copies!
+// make any copies of `BigInt`!
impl Minimum for BigInt {
fn min<'a>(&'a self, other: &'a Self) -> &'a Self {
unimplemented!()
// of course, need a `Display` bound on `T`.) Then you should be able to use them with `println!` just like you do
// with numbers, and get rid of the inherent functions to print `SomethingOrNothing<i32>` and `SomethingOrNothing<f32>`.
-//@ [index](main.html) | [previous](part06.html) | [next](main.html)
+//@ [index](main.html) | [previous](part06.html) | [next](part08.html)