Closure in map, printing a vector

help
1

hello I am trying to print a vec using map:

mod sort;

use std::io::{self, Write};

fn main() {

    //let i: i32 = -5;
    //println!("{}", i as usize);

    let mut a: Vec<i32> = vec![1, 2, 3];
    let k = *a.iter().max().unwrap() + 1;
    sort::mod_count_sort(&mut a, k);

    a.iter().map(|x| println!("{}", *x));

}

And vector never gets printed.

2

Maps are lazy, meaning that they are only computed when they are actually used.
The more appropriate method of printing that out would be putting println statement in a for-loop that iterates over a (The vec)
In this example, I print out the contents of the vec, and in this other example, I collect the map, meaning that it iterates through every possible item that the map could produce and puts them into a Vec<i32>. This runs the |x| {println!("{}", *x); *x} statement and therefore the items that the map outputs are actually calculated (In this example, the "calculation" actually prints them and returns the value).

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3

Be sure to pay attention to the warnings you're getting:

warning: unused `std::iter::Map` which must be used
 --> src/main.rs:4:5
  |
4 |     a.iter().map(|x| println!("{}", *x));
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: #[warn(unused_must_use)] on by default
  = note: iterator adaptors are lazy and do nothing unless consumed

You might want Iterator::for_each.

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