AppModule.kt

@Module
class AppModule(val app: Application) {

  @Provides
  @Singleton
  fun provideApplication(): Application = app

  @Provides
  @Singleton
  fun provideCryptocurrenciesDatabase(app: Application): Database = Room.databaseBuilder(app,
      Database::class.java, "cryptocurrencies_db").build()

  @Provides
  @Singleton
  fun provideCryptocurrenciesDao(database: Database): CryptocurrenciesDao = database.cryptocurrenciesDao()
}