Difference between calling a function in a lambda and function references

Question

In the following code (in kotlin)

fun greet(){
    print("Hello!  ")
}
fun salute(){
    print("Have a nice day ")
}


fun main(args: Array<String>){

    //val todoList: List<()->Unit> = listOf(::greet,::salute)
    val todoList: List<()->Unit> = listOf({greet()},{salute()})

    for(task in todoList){
        task()
    }    
}

What is the significance of using the first way that is now commented (Function references) against using the second way (just calling the functions in a lambda)

As far of results both print "Hello! Have a nice day"

In this case it's not better. In general: 1) Fewer brackets (in more complicated expressions you will fill it). 2) For functions with multiple arguments you won't need to re-pass them, so you will win some space (and your expression will become simpler). — , Jul 18 '19 at 02:48
It's essentially equivalent. Use whichever you think reads better. — Louis Wasserman, Jul 18 '19 at 03:08

JsonSong · Answer 1 · 2019-07-18T05:59:31.060

1

you can check the signature by your ide .

:: is reflect operation to get KFunction type from method

val f2 = { greet() } is that : you create a new lambda statement like

() ->  () -> Unit

and then call the inland lambda

edited Jul 18 '19 at 05:59

answered Jul 18 '19 at 03:07

JsonSong

328
2
14

Difference between calling a function in a lambda and function references

1 Answers1