Functional Kotlin

Promises with Kovenant 

Another option to write asynchronous code is to use promises. A promise is similar to a future (in many frameworks, futures and promises are synonymous), as it represents a computation that may complete in the future. We have a blocking method to obtain its result, but we can also react to its result, callback style. 

Kovenant (http://kovenant.komponents.nl/) is an implementation of promises for Kotlin:

import nl.komponents.kovenant.Promiseimport nl.komponents.kovenant.taskimport nl.komponents.kovenant.thenclass PromiseUserService(private val userClient: UserClient,                   private val factClient: FactClient,                   private val userRepository: UserRepository,                   private val factRepository: FactRepository) : UserService {   override fun ...