Zig's interface? - generic comptime

const std = @import("std");

const Animal = struct {
    pub fn talk(self: anytype) void {
        self.talk();
    }
};

const Cat = struct {
    anger_level: usize,

    pub fn talk(self: Cat) void {
        std.debug.print("[Cat] Meow! (anger Lv {})\n", .{self.anger_level});
    }
};

const Dog = struct {
    name: []const u8,

    pub fn talk(self: Dog) void {
        std.debug.print("[Dog] I'm a {s}\n", .{self.name});
    }
};

const Panda = struct {
    pub fn talk(_: Panda) void {
        std.debug.print("[Panda] Hahaha!\n", .{});
    }
};

fn do(self: anytype) void {
    self.talk();
}

pub fn main() !void {
    const cat = Cat{ .anger_level = 100 };
    Animal.talk(cat);
    const dog = Dog{ .name = "lilly" };
    Animal.talk(dog);
    const panda = Panda{};
    Animal.talk(panda);

    do(cat);
    do(dog);
    do(panda);
}