trait allows multiple inheritance.
A Trait is basically a collection of methods,
so the body of a Trait looks just like a class body.
Traits also work great as interfaces.
Declare a class to implement a trait with class trait Foo.
This copies the methods from the trait to the class.
Traits can have super-traits.
Just like for classes, static methods of traits are inherited.
A = trait static get static 0 get foo 1 B = trait A get bar 2 C = class get baz 3 Bar = class extends C trait B bar = new Bar . Bar.static . bar.foo . bar.bar . bar.baz
trait!
trait! lets an existing type implement a Trait.
Trait uses a Symbol to mark implementors, so this is safe.
You can also define methods (including statics) in a block. This is intended for traits with associated methods — for example, a @ must implement iterator.
pol = poly \ 0 Num/Str = trait pol \ 1 trait! Number Num/Str trait! String Num/Str static || Sometimes implementing a trait means implementing static methods. || For example, any `@` type should implement `empty`. get foo 0 pol \ 2 . and 0:Num/Str "":Num/Str . not []:Num/Str . pol [] || the poly's default . pol 12 || Num/Str implementation . pol "" || String implementation (overrides Num/Str implementation)