A lightning talk introducing the basics of the Kotlin programming language

1. Derping.with
{ Kotlin }

5. // JVM
// Android
// JavaScript
// LLVM

6. // Actually has libraries
// Actually has tooling
// Actually has traction

7. // Variables

8. val name = "Ross"
var age = 32

9. val name: String = "Ross"
var age: Int = 32

10. val name = "Ross"
var age = 32

11. // Functions

12. fun answer(): Int {
return 42
}

13. fun answer(): Int = 42

14. fun answer() = 42

15. fun answer(): Int {
return 42
}

16. // Parameters

17. fun greet(name: String): String {
return "Hello " + name
}

18. // String Interpolation

19. fun greet(name: String): String {
return "Hello " + name
}

20. fun greet(name: String): String {
return "Hello $name"
}

21. // Named Parameters

22. fun greet(name: String): String {
return "Hello $name"
}

23. fun greet(name: String,
): String {
return "Hello $name"
}

24. fun greet(name: String,
greeting: String = "Hello"
): String {
return "Hello $name"
}

25. fun greet(name: String,
greeting: String = "Hello"
): String {
return "$greeting $name"
}

26. // Calling a function

27. greet("Ross")
greet("Ross", greeting="Aloha")

28. // Classes

29. class Game()
{
}

30. class Game()
{
fun join(user: UserName)
{
}
}

31. val myGame = Game()

32. // Dependencies

33. class Game()
{
fun join(user: UserName)
{
}
}

34. class Game(val logger: Logger)
{
fun join(user: UserName)
{
}
}

35. class Game(val logger: Logger)
{
fun join(user: UserName)
{
this.logger.log("foo")
}
}

36. class Game(val logger: Logger)
{
fun join(user: UserName)
{
logger.log("foo")
}
}

37. class Game(private val logger: Logger)
{
fun join(user: UserName)
{
logger.log("foo")
}
}

38. // Neat Class Things

39. // Neato Constructor Options
// Enums
// Sealed Classes
// Delegation
// Properties
data class Name(val first: String, val last: String)

40. // Null Safety

41. fun greet(name: String): String {
return "Hello $name"
}

42. fun greet(name: String?): String {
return "Hello $name"
}

43. fun greet(name: String?): String {
return "Hello $name"
}
“Hello Ross”

44. fun greet(name: String?): String {
return "Hello $name"
}
“Hello null”

45. fun greet(name: String?): String {
return "Hello $name"
}

46. fun greet(name: String?): String {
return "Hello ${name.toUpperCase()}"
}

47. fun greet(name: String?): String {
return "Hello ${name.toUpperCase()}"
}

48. fun greet(name: String?): String {
return "Hello $name"
}

49. fun greet(name: String?): String {
if (name == null) {
return "STRANGER DANGER"
}
return "Hello $name"
}

50. fun greet(name: String?): String {
return "Hello $name"
}

51. fun greet(name: String?): String {
return "Hello ${formatName(name)}"
}
fun formatName(name: String): String {
return name.toUpperCase();
}

52. fun greet(name: String?): String {
return "Hello ${formatName(name)}"
}
fun formatName(name: String): String {
return name.toUpperCase();
}

53. fun greet(name: String?): String {
return "Hello ${formatName(name)}"
}
fun formatName(name: String): String {
return name.toUpperCase();
}

54. address?.postCode()?.suffix()
age ?: 29

55. // Java Interop

56. import myutils.tableflip
import java.time.LocalDate
val now = LocalDate.now()

57. //Extension Functions

58. fun BoardGame.tableFlip(): String {
return "(ノ°Д° ︵）ノ ┻━┻"
}
val game = BoardGame()
game.tableFlip()

60. fun BoardGame.tableFlip(): String {
return "(ノ°Д° ︵）ノ ┻━┻"
}
val game = BoardGame()
game.tableFlip()

61. import nerdstuff.BoardGame
import myutils.tableflip

62. import java.time.LocalDate
fun LocalDate.yesterday(): LocalDate {
return minusDays(1)
}
val now = LocalDate.now()
val yesterday = now.yesterday()

63. // Collections

64. val nums = listOf(1, 2, 3)
nums.map( )

65. val nums = listOf(1, 2, 3)
nums.map({x: Int -> x * 2})
nums.map({x -> x * 2})
nums.map() {x -> x * 2}
nums.map {x -> x * 2}
nums.map { it * 2 }

66. // DSLs

67. routing {
get("/") {
call.respondText("Hello, world!")
}
post("/register") {
// do stuff
}
}

68. val routing = RoutingBuilder()
routing.get(
{call: Call ->
call.respondText("Hello World!")
}
)
routing.post(/* do stuff */)

69. html {
head {
title { +"Demo" }
}
body {
h1 { +"Welcome!" }
a(href="/FAQ") { +"FAQ" }
}
}

70. // Kotlin & Me & You

71. // Thanks
// @rosstuck
// me@rosstuck.com