add-drama.ts

import {InjectionToken} from '@angular/core'
import {Http} from '@angular/http'
import {Observable} from 'rxjs/Rx'

//simple fn
export function AddDrama(value:string){
  return `${value}!!!`
}

export const AddDramaProvider = {
  provide: AddDrama,
  useValue: AddDrama //provide the AddDrama fn when it's injected
}


//complex fn with deps

//export the type signature
export type TransmitDramaFn = (value:string) => Observable<string>

//factory fn - like app.factory() in angularjs
export function DramaTransmitterFactory(http:Http): TransmitDramaFn{

  function sendDrama(value:string){
    return http.post('http://omg.com', value).map(res => res.json());
  }

  return sendDrama;
}


export const DramaTransmitter:InjectionToken<TransmitDramaFn> = new InjectionToken('DramaTransmitter');

export const DramaTransmitterProvider = {
  provide: DramaTransmitter,
  useFactory: DramaTransmitterFactory,
  deps: [Http, AddDrama]
}

component.ts

import { Component, Inject } from '@angular/core';
import { AddDrama, DramaTransmitter, TransmitDramaFn } from './tokens'

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'app';
  constructor(
    //use @Inject when not using classes as DI Token
    @Inject(AddDrama) addDrama:typeof AddDrama, //typeof or inline - addDrama:(v:string) => string
    @Inject(DramaTransmitter) transmit:TransmitDramaFn //use exported type 
  ){
    let dramaHello = addDrama('hello');
    transmit(dramaHello)
  }
}

module.ts

import {DramaTransmitterProvider, AddDramaProvider} from './add-drama'

@NgModule({
  providers: [ DramaTransmitterProvider, AddDramaProvider ]
})
export class SomeModule {}