Introduce syntax of Kotlin

1. Functions, Anonymous Functions
and the Function Type
Kotlin Study Group
John

2. Hi, I am John
- Android Developer
- Work on Rakuten Viki
- Use Kotlin for 2 years
- Linkedin:
https://www.linkedin.com/in/chang-john-0a95237a/

3. Outline
- What’s a Function?
- Call a Function
- Anatomy of a Function
- Function Header
- Visibility Modifier
- Function Name declaration
- Function Return Type
- Function Body

4. Outline
- Named Functions v.s Anonymous Functions
- Function Type
- Implicit returns
- it keyword
- Function Inference Support
- High-Order Function
- Lambda/Function Reference/Anonymous Function
- Function Inlining
- Closure Behavior
- Function Support: Kotlin v.s Java
- Q&A

5. Q&A
- How to achieve backticks symbol naming?
- How Top level function in Kotlin is achieved on JVM?
- How default arguments in Kotlin is achieved on JVM?
- How naming function arguments in Kotlin is achieved on JVM?
- How to achieve Nothing type and TODO() function?

6. What’s a Function?

7. Call a Function

8. Anatomy of a Function

9. - Visibility modifier
- Use private/internal/public
- Without specify any visibility modifier, public is used by default
- Visibility Modifier definition
- Function Name
- Name by camel case with no underscores for convention.
- Surround using backticks symbol, like fun `This is my function`() { .. .}
- Function Parameters
- The Format is variableName: Type in order. No need to add val/var in advance.
- Default arguments, like fun log(tag: String = “”, msg: String) { … }
- Naming Function Arguments, like log(tag = “Main”, msg = “print function”)

10. - Function Parameters
- Function Overloading

11. - Return Type
- Return type can any type, primitive or class
- If no specify return type, default type is Unit
- Nothing type lets the compiler know that a function is guaranteed to NEVER successfully
complete, like TODO()

12. - Function Body
- Function Scope
- Single-Expression Function

13. Named Function v.s Anonymous Function

14. Function Type

15. Function Arguments

16. Function Arguments - it keyword

17. Type Inference Support

18. Define a Function That Accepts a Function

19. If we define a function that accepts a function, we can call it
high-order function

20. If we define a function that accepts a function, we can call it
high-order function
Reference from High-Order Function and Lambda

21. How to pass a instance of function type as arguments?
Use Lambda

22. If function type is last parameter, it even pass Lambda with
the shorthand syntax

23. How to pass a instance of function type as arguments?
Use Function Reference

24. How to pass a instance of function type as arguments?
Use Anonymous Function

25. Function Inlining

26. Function Inlining - without inline

27. Function Inlining - use inline

28. Closure Behavior

29. Function Support: Kotlin v.s Java
- Java version

30. Function Support: Kotlin v.s Java
- Kotlin version

31. Q&A

32. How to achieve backticks symbol naming on JVM?
Kotlin
Java

33. How Top level function in Kotlin is achieved on JVM?
Kotlin
Java

34. How default arguments in Kotlin is achieved on JVM?
Kotlin
Java

35. How naming function arguments in Kotlin is achieved on
JVM?
Kotlin
Java

36. How to achieve Nothing type and TODO() function?
TODO
Nothing