Example of using lists.

list.rs

// Polymorphic lists
// Compile with "rustc -o list list.rs"

// more recent versions of the compiler need this for @ pointers
#[feature(managed_boxes)];

// enable macros
#[feature(macro_rules)];


enum List<A> {
    Empty,
    Cons(A, @List<A>)
}

fn length<A>(l: @List<A>) -> uint {
    match *l {
        Empty => 0,
        Cons(_, rest) => 1 + length(rest)
    }
}

fn length_acc<A>(l: @List<A>, acc: uint) -> uint {
    match *l {
        Empty => acc,
        Cons(_, rest) => length_acc(rest, acc + 1)
    }
}

macro_rules! list(
    ( $e:expr, $($rest:expr),+ ) => ( @Cons($e, list!( $( $rest ),+ )) );
    ( $e:expr ) => ( @Cons($e, @Empty) );
    () => ( @Empty )
)

fn sum_int_list(l: @List<int>) -> int {
    match *l {
        Empty => 0,
        Cons(x, rest) => x + sum_int_list(rest)
    }
}

fn main() {
    let l = @Cons("3", @Cons("little", @Cons("strings", @Empty)));
    println!("Length of l is {}", length(l));
    println!("Length of l is {}", length_acc(l, 0));

    let l2 = list!(5, 4, 4, 3);
    println!("Length of l2 is {}", length(l2));
    println!("Sum of l2 is {}", sum_int_list(l2));
}