AngularJS Typed Script Provider

Provider.ts

// Interface describing the members that the provider's service offers
interface IGreetingService {
    getGreeting(): string;
}
 
// The following class represents the provider
class GreetingService implements ng.IServiceProvider {
    private greeting = "Hello World!";
 
    // Configuration function
    public setGreeting(greeting: string) {
        this.greeting = greeting;
    }
 
    // Provider's factory function
    public $get() : IGreetingService {
        return {
            getGreeting: () => { return this.greeting; }
        };
    }
}
 
// Define a controller depending our provider
class ControllerNeedingProvider {
    constructor($scope, GreetingService: IGreetingService) {
        $scope.Greeting = GreetingService.getGreeting();
    }
}
 
angular.module("ProviderApp", [])
    // Define provider
    .provider("GreetingService", GreetingService)
    // Configure provider (note the suffix "Provider" here)
    .config((GreetingServiceProvider: GreetingService) => {
        GreetingServiceProvider.setGreeting("Hello Provider");
    })
    .controller("ControllerNeedingProvider", ControllerNeedingProvider);