Scala--pack your Future[T]; Kotlin is coming! (Kotlin TLV)

Many people ask why Kotlin is better than Scala, or sometimes claims the opposite. We will discuss all those extra features which are present in Scala but absent in Kotlin, and some more advantages of Kotlin. In this talk, we will also recap some of the awesome features that make Kotlin a great language to use.

Transcript

1. Scala--pack your Future[T]; 
 Kotlin is coming! Ohad Shai Software Developer && Team Leader @ Outbrain
2. Disclaimer @lifey
3. About Me • Developing Software since 2005 • Mainly in Java and JVM languages • Works on backend systems • Maintainer of kotlin-logging open-source lib • Kotlin advocate on my spare time since early in 2016
4. What is Kotlin • Statically typed Programming Language • Multi-Platform (JVM first, JS and Native) • Open Source • Developed by JetBrains since 2010 • Version 1.0 on Feb. 2016 • Official Android (Google) support since May 2017 https://medium.com/@octskyward/why-kotlin-is-my-next-programming-language-c25c001e26e3
5. Kotlin Features • Concise
6. Kotlin Features • Concise • Safe
7. Kotlin Features • Concise • Safe • Interoperable
8. Kotlin Features • Concise • Safe • Interoperable • Tool-friendly
9. Why Kotlin? • Scala – the good parts (And also other languages) • Practical • Tools, support • Community • Google adopted it
10. Side by side comparison Scala val hello: String = “hi" var hello: String = "hi" Kotlin val hello: String = “hi" var hello: String = "hi"
11. Side by side comparison Scala val hello = “hi" var hello = "hi" Kotlin val hello = “hi" var hello = "hi"
12. Case / data class Scala case class Service( name: String ) Kotlin data class Service( val name: String )
13. Case / data class Scala case class Service( name: String ) // you will get: - toString() - equals() / hashCode() - copy() Kotlin data class Service( val name: String ) // you will get: - toString() - equals() / hashCode() - copy()
14. Case / data class Scala case class Service( name: String ) Kotlin data class Service( val name: String ) // you will get: - toString() - equals() / hashCode() - copy() • Differences – new keyword – toString – Java interop (getter setter) – unapply
15. Null safety Scala var hello: Option[String] = None Kotlin var hello: String? = null
16. Nullable Types val world: String? = null println(world.toUpperCase()) // In Java you will get NPE // In Kotlin you will get compilation error
17. Nullable Types val world: String? = null if (world != null) { println(world.toUpperCase()) }
18. Nullable Types val world: String? = null println(world.toUpperCase())
19. Nullable Types val world: String? = null println(world?.toUpperCase())
20. Nullable Types val world: String? = null println(world?.toUpperCase())
21. Null safety Scala var hello: Option[String] = None Kotlin var hello: String? = null
22. Singleton Scala object Single { } Kotlin object Single { }
23. Enum Scala Kotlin enum class Fruits { Apple, Banana }
24. Implicit class / Extension method Scala 5.hours() Kotlin 5.hours()
25. Implicit class / Extension method Scala object Helpers { implicit class IntMillis(x: Int) { def hours() = TimeUnit.HOURS.toMillis(x) } } … 5.hours() Kotlin fun Int.hours() = TimeUnit.HOURS.toMillis( this.toLong()) … 5.hours()
26. What’s wrong with Scala?
27. What’s wrong with Scala? • Readability sucks.
28. What’s wrong with Scala? • Readability sucks. Examples: – Collections  //Kotlin fun <T, R> map(transform: (T) -> R): List<R>
29. What’s wrong with Scala? • Readability sucks. Examples: – Collections  def map[B, That](f: A => B) (implicit bf: CanBuildFrom[Repr, B, That]): That
30. What’s wrong with Scala? • Readability sucks. Examples: – Collections – Implicit conversions
31. What’s wrong with Scala? • Readability sucks. Examples: – Collections – Implicit conversions – Operator overloading
32. What’s wrong with Scala? • Readability sucks. Examples: – Collections – Implicit conversions – Operator overloading – Underscore 
33. What’s wrong with Scala? • Scala has levels of features • There is more than one way to do it
34. What’s wrong with Scala? • Scala has levels of features • There is more than one way to do it • Readability sucks
35. What’s wrong with Scala? • Backward compatibility – “Scala isn’t binary compatible between minor versions.”
36. What’s wrong with Scala? • Backward compatibility – “Scala isn’t binary compatible between minor versions.”
37. What’s wrong with Scala? • Compilation time > mvn clean install
 … [INFO] Module................................................. SUCCESS [ 7.115 s]
 [INFO] Module................................................. SUCCESS [ 32.680 s]
 [INFO] Module................................................. SUCCESS [01:05 min]
 [INFO] Module................................................. SUCCESS [ 1.080 s]
 [INFO] Module................................................. SUCCESS [ 44.077 s]
 [INFO] Module................................................. SUCCESS [ 1.234 s]
 [INFO] Module................................................. SUCCESS [ 3.410 s]
 [INFO] Module................................................. SUCCESS [ 26.661 s]
 [INFO] Module................................................. SUCCESS [ 45.317 s]
 [INFO] Module................................................. SUCCESS [ 46.435 s]
 [INFO] Module................................................. SUCCESS [ 37.738 s]
 [INFO] Module................................................. SUCCESS [ 14.198 s]
 [INFO] ------------------------------------------------------------------------
 [INFO] BUILD SUCCESS
 [INFO] ------------------------------------------------------------------------
 [INFO] Total time: 06:37 min (Wall Clock)
 [INFO] Finished at: 2017-07-02T15:13:48+03:00
 [INFO] Final Memory: 970M/2498M
 [INFO] ------------------------------------------------------------------------ >
38. What’s wrong with Scala? • Compilation time > mvn clean install | grep min 
 [INFO] Scala............................................... SUCCESS [01:05 min]
 [INFO] Scala............................................... SUCCESS [01:30 min]
 [INFO] Scala............................................... SUCCESS [02:29 min]
 [INFO] Scala............................................... SUCCESS [01:16 min]
 [INFO] Scala............................................... SUCCESS [01:17 min]
 [INFO] Scala............................................... SUCCESS [01:16 min]
 [INFO] Scala............................................... SUCCESS [01:25 min]
 [INFO] Scala............................................... SUCCESS [01:22 min]
 [INFO] Scala............................................... SUCCESS [02:21 min]
 [INFO] Scala............................................... SUCCESS [01:05 min]
 [INFO] Scala............................................... SUCCESS [01:23 min]
 [INFO] Scala............................................... SUCCESS [01:15 min]
 [INFO] Scala............................................... SUCCESS [01:28 min]
 [INFO] Scala............................................... SUCCESS [01:13 min]
 [INFO] Scala............................................... SUCCESS [01:11 min]
 [INFO] Scala............................................... SUCCESS [01:05 min]
 [INFO] Total time: 06:37 min (Wall Clock) >
39. What’s wrong with Scala? • Readability • Backward compatibility • Compilation time
40. Some more cool features https://imgflip.com/memetemplate/105181795/cool-guy-zone
41. When Expression when (object) { 1 -> "One" "Hello" -> "Greeting" is Long -> "Long" in 2..10 -> "obj is in the range" else -> "Unknown" }
42. Collections val fruits = listOf("banana", "avocado", "apple", "kiwi") fruits .filter { it.startsWith("a") } .sortedBy { it } .map { it.toUpperCase() } .forEach { println(it) }
43. Coroutines • Lightweight threads • Suspend-able computation • Writing imperative/blocking style • Executed ‘similar’ to callback style • Implements: async/await, actors, channels, and more…
44. Take Home • Scala • Readability • Backward compatibility • Compilation • Kotlin • A better practical Scala
45. Question? Like Kotlin? We’re hiring!
46. Thank You! @OhadShai
47. Back-Up
48. Coroutines val time = measureTimeMillis { val one = async(CommonPool) { doSomethingUsefulOne() } val two = async(CommonPool) { doSomethingUsefulTwo() } println("The answer is ${one.await() + two.await()}”) } println("Completed in $time ms") The answer is 42 Completed in 1017 ms
49. Coroutines val jobs = List(100_000) { index -> async(CommonPool) { delay(1000L) index } } println( jobs.sumBy { it.await() } )