Feature: Multiple class extensions (and inheritance).

[john-bv]

Typesharp will allow multilevel inheritance, aka you will be able to inherit multiple classes by abstraction with the as keyword on super.
Ex:

class TaxiRides extends Queue<Ride>, Date, Mutex {
    public constructor() {
         super(); // Queue
         super as Date();
         super as Mutex();
    }
}
// Where queue is:
class Queue<T> {
    private next_in_list: T[];

    public constructor() {
         this.next_in_list = [];
    }

    public function queue(item: T): void {
         this.next_in_list.add(item);
    }

    public function dequeue(): T? {
         return this.next_in_list.shift() || null;
    }
}