Understanding Kotlin - KTM JS Meetup 2017

Understanding the Kotlin language. A brief guide to the language.

Transcript

1. Kotlin Understanding
2. Types
5. Basic Syntax
6. var name: String = “Rakeeb”
7. var name: String = “Rakeeb” Mutability/ Immutability
8. val name: String = “Rakeeb” Mutability/ Immutability
9. val name: String = “Rakeeb” String Type Declaration
10. val name: String? = null Nullable String Type Declaration
11. fun getName(id: Int): String { ... return “Rakeeb” }
12. fun getName(id: Int): String { ... return “Rakeeb” } Keyword
13. fun getName(id: Int): String { ... return “Rakeeb” } Function name with parameter
14. fun getName(id: Int): String { ... return “Rakeeb” } Return type
15. fun getName(id: Int): String { ... return “Rakeeb” } Function body
16. class Person(val firstName: String, val lastName: String)
17. class Person(val firstName: String, val lastName: String) Constructor
18. fun getPerson(id: Int): Person { return Person(“A..”, “B..”) }
19. Type Inference
20. var name = “Rakeeb”
21. fun getName() = “Rakeeb”
22. Extensions
23. val name = “Rakeeb, Rajbhandari”
24. class Person(val firstName: String, val lastName: String)
25. fun String.getPerson(): Person { val subStr = split(“,”) return Person(subStr[0], subStr(1)) }
26. fun String.getPerson(): Person { val subStr = split(“,”) return Person(subStr[0], subStr(1)) } Extending String
27. fun String.getPerson(): Person { val subStr = split(“,”) return Person(subStr[0], subStr(1)) }
28. fun String.getPerson(): Person { val subStr = split(“,”) return Person(subStr[0], subStr(1)) }
29. val name = “Rakeeb, Rajbhandari” val rakeeb = name.getPerson()
30. val name = “Rakeeb, Rajbhandari” val rakeeb = name.getPerson()
31. Higher Order Functions
32. fun XMLHttpRequest.getPerson(): Person { ... }
33. fun XMLHttpRequest.getPerson(): Person { open(“GET”, URL, false) ... }
34. fun XMLHttpRequest.getPerson(): Person { open(“GET”, URL, false) // map request object to person? }
35. fun XMLHttpRequest.getPerson(mapper: (String) ➝ Person): Person { ... }
36. fun ...(mapper: (String) ➝ Person): Person { ... }
37. fun XMLHttpRequest.getPerson(mapper: (String) ➝ Person): Person { open(“GET”, URL, false) return mapper(responseText) }
38. fun XMLHttpRequest.getPerson(mapper: (String) ➝ Person): Person { open(“GET”, URL, false) return mapper(responseText) }
39. val client = XMLHttpRequest() val rakeeb = client.getPerson { mapper.mapToPerson(it) }
40. val client = XMLHttpRequest() val rakeeb = client.getPerson { mapper.mapToPerson(it) }
41. val client = XMLHttpRequest() val rakeeb = client.getPerson { mapper.mapToPerson(it) }
42. fun ...(mapper: (String) ➝ Person): Person { ... }
43. val client = XMLHttpRequest() val rakeeb = client.getPerson { mapper.mapToPerson(it) }
44. fun XMLHttpRequest.getPerson(mapper: XMLHttpRequest.() ➝ Person): Person { ... }
45. fun XMLHttpRequest.getPerson(mapper: XMLHttpRequest.() ➝ Person): Person { open(“GET”, URL, false) return this.mapper() }
46. val client = XMLHttpRequest() val rakeeb = client.getPerson { mapper.mapToPerson(responseText) }
47. Why Kotlin?
48. The compiler is your friend
49. Get the best features from Java *for free
50. Multiplatform Baby!
51. Links
52. • Presented by Rakeeb. • Medium • Twitter • Github • Demo App • Todo App [Kotlin JS] • Random Name Picker App [React]