Rust code shared from the playground

playground.rs

use std::boxed::Box;

fn a(value: usize) -> Box<[usize]> {
    vec![0; value].into_boxed_slice()
}

fn main() {
    let val = a(5);
    let test = Test {
        arr: val,
    };
    
    println!("{:?}", test);
    
    let val = a(10);
    let test = Test {
        arr: val,
    };
    
    println!("{:?}", test);
}

#[derive(Debug)]
struct Test {
    arr: Box<[usize]>,
}

https://www.reddit.com/r/rust/comments/3gp0tl/dynamic_fixed_sized_arrays/