Rust 是否具有与 Python 的字典的类似功能

在下面的Python中，几个文件被读取，它们的内容被用作字典的值(以文件名为键)，我们如何将其翻译为Rust？

countries = {region: open("{}.txt".format(region)).read() for region in ["canada", "usa", "mexico"]}

我的try 如下图所示，但我想知道是否有可能实现一个单行的惯用解决方案.

use std::{
    fs::File,
    io::{prelude::*, BufReader},
    path::Path,
    collections::HashMap,
};

macro_rules! map(
    { $($key:expr => $value:expr),+ } => {
        {
            let mut m = HashMap::new();
            $(
                m.insert($key, $value);
            )+
            m
        }
     };
);

fn lines_from_file<P>(filename: P) -> Vec<String>
where
    P: AsRef<Path>,
{
    let file = File::open(filename).expect("no such file");
    let buf = BufReader::new(file);
    buf.lines()
        .map(|l| l.expect("Could not parse line"))
        .collect()
}

fn main() {
    let _countries = map!{ "canada" => lines_from_file("canada.txt"),
                           "usa"    => lines_from_file("usa.txt"),
                           "mexico" => lines_from_file("mexico.txt") };
}