join-string 0.3.0

Join the elements of iterators as a string, interspersing a separator between all elements.
Documentation 
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use join_string::Join;

pub fn reverse_words(s: impl AsRef<str>) -> String {
    s.as_ref()
        .split_whitespace()
        .map(|s| s.chars().rev().join(""))
        .join(" ")
        .into_string()
}

fn main() {
    println!("{}", reverse_words("foo bar baz"));

    println!(
        "{}",
        "foo bar baz"
            .split_whitespace()
            .map(|s| s.chars().rev().join(""))
            .join(" ")
    );

    println!(
        "{}",
        "foo bar baz"
            .split_whitespace()
            .map(|s| s
                .chars()
                .rev()
                .map(|c| char::from_u32(c as u32 + 1).unwrap_or('?'))
                .join(""))
            .join(" ")
    );

    // inefficient temporary strings
    println!(
        "{}",
        "foo bar baz"
            .split_whitespace()
            .map(|s| s.chars().rev().map(|c| format!("<{c}>")).join(""))
            .join(" ")
    );

    // inefficient temporary strings
    println!(
        "{}",
        std::env::args()
            .map(|s| s.chars().rev().collect::<String>())
            .join(" ")
            .into_string()
    );
}