fn main() {
    println!("{:?}", {
        (&[1, 2, 3]).iter().map(|&x: usize| x*2).sum() as usize
    });
}


/* ~~~~=== stderr ===~~~~
   Compiling playground v0.0.1 (file:///playground)
error[E0308]: mismatched types
 --> src/main.rs:5:34
  |
5 |         (&[1, 2, 3]).iter().map(|&x: usize| x*2).sum() as usize
  |                                  ^^ expected usize, found reference
  |
  = note: expected type `usize`
             found type `&_`
  = help: did you mean `x: &usize`?

error[E0631]: type mismatch in closure arguments
 --> src/main.rs:5:29
  |
5 |         (&[1, 2, 3]).iter().map(|&x: usize| x*2).sum() as usize
  |                             ^^^ --------------- found signature of `fn(usize) -> _`
  |                             |
  |                             expected signature of `fn(&{integer}) -> _`

error[E0599]: no method named `sum` found for type `std::iter::Map<std::slice::Iter<'_, {integer}>, [closure@src/main.rs:5:33: 5:48]>` in the current scope
 --> src/main.rs:5:50
  |
5 |         (&[1, 2, 3]).iter().map(|&x: usize| x*2).sum() as usize
  |                                                  ^^^
  |
  = note: the method `sum` exists but the following trait bounds were not satisfied:
          `std::iter::Map<std::slice::Iter<'_, {integer}>, [closure@src/main.rs:5:33: 5:48]> : std::iter::Iterator`
          `&mut std::iter::Map<std::slice::Iter<'_, {integer}>, [closure@src/main.rs:5:33: 5:48]> : std::iter::Iterator`

error: aborting due to 3 previous errors

Some errors occurred: E0308, E0599, E0631.
For more information about an error, try `rustc --explain E0308`.
error: Could not compile `playground`.

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

*/

/* ~~~~=== stdout ===~~~~

*/