Very basic linked list in Rust

linked_list.rs

use std::fmt;

/*
Made this to experiment with making abstract data structures in Rust.

I'm not entirely convinced that it's necessary to use Box here...
*/

fn flip(p: &Point) -> Point {
    Point{ x: p.y, y: p.x }
}

fn map_ll<T, F>(list: &LinkedList<T>, func: F) -> LinkedList<T> where F: Fn(&T) -> T {
    LinkedList {
        head: func(&list.head),
        tail: match list.tail {
            Some(ref ll) => Some(Box::new(map_ll(&ll, func))),
            None => None
        }
    }
}


struct Point {
    x: i32,
    y: i32,
}

impl fmt::Display for Point {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "(x: {}, y: {})", self.x, self.y)
    }
}


struct LinkedList<T> {
    head: T,
    tail: Option<Box<LinkedList<T>>>,
}

impl <T: fmt::Display> fmt::Display for LinkedList<T> {
    fn fmt(&self, f: &mut fmt:: Formatter) -> fmt::Result {
        match self.tail {
            Some(ref ll) => write!(f, "{} -> {}", self.head, ll),
            None => write!(f, "{}", self.head),
        }
    }
}


fn main() {
    let p = Point { x: 10, y: 20 };
    let p2 = Point { x: 30, y: 40 };
    
    let l = LinkedList { head: p, tail: Some(Box::new(LinkedList { head: p2, tail: None })) };
    let l2 = map_ll(&l, flip);
    
    println!("linked list: {}", l);
    println!("linked list (flipped): {}", l2);
}