Casting idiom type to another idiom type

1

I'm trying to get use of the new-type-idiom as below:

struct Kilometers(i32);

By creating the below playground that allow creating item in Kilometers then convert in to meters:

use std::ops::Mul;

struct Kilometers(i32);
struct Meters(i32);

pub trait Convert {
    fn to_meter(self) -> Meters;
}

impl Convert for Kilometers {
    fn to_meter(self) -> Meters {
            self * 1_000.0
    }
}

fn main() {
    let x = Kilometers(5);
    println!("{} Kilometers = {} Meters", x, x.to_meter());
}

But I got the below errors:

   Compiling playground v0.0.1 (/playground)
warning: unused import: `std::ops::Mul`
 --> src/main.rs:1:5
  |
1 | use std::ops::Mul;
  |     ^^^^^^^^^^^^^
  |
  = note: #[warn(unused_imports)] on by default

error[E0369]: binary operation `*` cannot be applied to type `Kilometers`
  --> src/main.rs:12:13
   |
12 |             self * 1_000.0
   |             ^^^^^^^^^^^^^^
   |
   = note: an implementation of `std::ops::Mul` might be missing for `Kilometers`

error[E0277]: `Kilometers` doesn't implement `std::fmt::Display`
  --> src/main.rs:18:43
   |
18 |     println!("{} Kilometers = {} Meters", x, x.to_meter());
   |                                           ^ `Kilometers` cannot be formatted with the default formatter
   |
   = help: the trait `std::fmt::Display` is not implemented for `Kilometers`
   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
   = note: required by `std::fmt::Display::fmt`

error[E0277]: `Meters` doesn't implement `std::fmt::Display`
  --> src/main.rs:18:46
   |
18 |     println!("{} Kilometers = {} Meters", x, x.to_meter());
   |                                              ^^^^^^^^^^^^ `Meters` cannot be formatted with the default formatter
   |
   = help: the trait `std::fmt::Display` is not implemented for `Meters`
   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
   = note: required by `std::fmt::Display::fmt`

error: aborting due to 3 previous errors

Some errors occurred: E0277, E0369.
For more information about an error, try `rustc --explain E0277`.
error: Could not compile `playground`.

To learn more, run the command again with --verbose.
2

A possible version:

#[derive(Debug, Copy, Clone)]
pub struct Kilometers(u64);

#[derive(Debug, Copy, Clone)]
pub struct Meters(u64);

pub trait Convert {
    fn to_meter(self) -> Meters;
}

impl Convert for Kilometers {
    fn to_meter(self) -> Meters {
            Meters(self.0 * 1_000)
    }
}

fn main() {
    let x = Kilometers(5);
    println!("{:?} = {:?}", x, x.to_meter());
}
3

That needs to be self.0 * 1_000.0 to work with the inner number, rather than the wrapper.