join-string

Reference

A simple crate to join the elements of iterators as a string, interspersing a separator between all elements.

This is done somewhat efficiently, if possible, meaning if the iterator is cheaply clonable you can directly print the result of Join::join() without creating a temporary String in memory.

use join_string::Join;

assert_eq!(
    "foo bar baz".split_whitespace().join(", ").into_string(),
    "foo, bar, baz");

println!("{}",
    "foo bar baz".split_whitespace()
        .map(|s| s.chars().rev().join(""))
        .join(' '));
// Output: oof rab zab

Note that the standard library already provides a similar Join trait on slices, but not on interators, and the standard library version always directly returns a new String. And then there are multiple other similar crates that however work a bit differently, e.g. having more restrictions on element and separator types or always returning a String.