Rust code shared from the playground

playground.rs

#![feature(box_syntax, box_patterns)]

use std::cmp::max;

// Recursive structs must be referenced or be Box'd
enum Tree<T: PartialOrd> {
    Empty,
    Node(T, Box<Tree<T>>, Box<Tree<T>>)
}

impl<T: PartialOrd> Tree<T> {
    fn insert(self, x: T) -> Tree<T> {
        match self {
            Tree::Empty =>
                Tree::Node(x, Box::new(Tree::Empty), Box::new(Tree::Empty)),
            Tree::Node(value, left, right) => {
                if x < value {
                    Tree::Node(value, Box::new(left.insert(x)), right)
                } else {
                    Tree::Node(value, left, Box::new(right.insert(x)))
                }
            }
        }
    }
    
    fn depth(&self) -> i32 {
        match *self {
            Tree::Empty => 0,
            Tree::Node(_, ref left, ref right) =>
                1 + max(left.depth(), right.depth())
        }
    }
}


fn main() {
    let tree = Tree::Empty.insert(5).insert(4).insert(3).insert(6).insert(2);
    let num = tree.depth();
    print!("Depth is: {}", num);
}