gistfile1.rs

trait A { fn foo(&self); }

trait B<X:A> { fn bar(&self, @X); }

trait C<X:A, Y:B<X>> { fn baz(&self, @X, @Y); }

// This doesn't work, as trait bounds are not allowed in structure defn's.x
//   struct Cat<X:A, Y:B<X>> { x: @X, y: @Y }
// Workaround by putting the check elsewhere
struct Cat<X, Y> { x: @X, y: @Y }

impl<X:A, Y:B<X>> C<X,Y> for Cat<X,Y> {
    fn baz(&self, x_arg: @X, y_arg: @Y) {
        println("baz");
        self.x.foo();
        x_arg.foo();
        self.y.bar(x_arg);
        y_arg.bar(x_arg);
    }
}

struct Alpha(int);
struct Beta(int);

impl A for Alpha { fn foo(&self) { println("Alpha foo"); } }
impl B<Alpha> for Beta  { fn bar(&self, x:@Alpha) { println("Beta bar"); x.foo(); } }

fn main() {
    let x = @Alpha(1);
    let y = @Beta(2);
    let cat : Cat<Alpha, Beta> = Cat::<Alpha, Beta> { x: @Alpha(3), y: @Beta(4) };
    println(fmt!("Hello World %?", cat.baz(x, y)));
}

gistfile2.txt

% rustc ~/Dev/Rust/foo.rs && ~/Dev/Rust/foo 
baz
Alpha foo
Alpha foo
Beta bar
Alpha foo
Beta bar
Alpha foo
Hello World ()