Adding an append method to a singly linked list

Question

I was looking through the singly linked list example on rustbyexample.com and I noticed the implementation had no append method, so I decided to try and impleme

Answer 1

As the len method is implemented recursively, I have done the same for the append implementation:

fn append(self, elem: u32) -> List {
    match self {
        Cons(current_elem, tail_box) => {
            let tail = *tail_box;
            let new_tail = tail.append(elem);

            new_tail.prepend(current_elem)
        }
        Nil => {
            List::new().prepend(elem)
        }
    }
}

One possible iterative solution would be to implement append in terms of prepend and a reverse function, like so (it won't be as performant but should still only be O(N)):

// Reverses the list
fn rev(self) -> List {
    let mut result = List::new();
    let mut current = self;
    while let Cons(elem, tail) = current {
        result = result.prepend(elem);
        current = *tail;
    }

    result
}

fn append(self, elem: u32) -> List {
    self.rev().prepend(elem).rev()
}