Is there a way to get reference to lambda in its d...

# getting-started

[Sam]

Is there a way to get reference to lambda in its definition?

val lambda = { value : Int -> executor( value, this ) }

[stephan_marshay]

Do you want a reference to the lambda (to what purpose..?) or to the class containing the lambda?
In the second case, use this@myClass

[Sam]

reference to the lambda

[Sam]

is it even possible?

[Sam]

from a Java standpoint, it is just an implementation of Function1, so i'm guessing there should be way to get its this

[marstran]

No, you can't reference it directly. What do you need that for? There's probably a better way to solve your problem.

[Sam]

Ok, just trying out few things, nothing specific

[gcx11]

You could use reflection, like this

val lambda: (Int) -> String = { value : Int -> executor( value, ::lambda.get() ) }

fun executor(value: Int, body: (Int) -> String): String {
    return body(value)
}

fun main(args: Array<String>) {
    println(lambda(1))
}

[marstran]

In theory, you could kinda do it with a construct called a Y-combinator though. The idea is to let the function take itself as a parameter.

[Sam]

Interesting, will check that out

[marstran]

@gcx11 For some reason, that seems to compile only when lambda is a top level property.

[marstran]

Probably because a local val won't have a getter.

[Sam]

yeah, same for me too

[marstran]

I found this implementation of the Y-combinator here: https://gist.github.com/jubinjacob19/99989899ddb2d8e1d1055730e6ecace4

fun <In, Out> y(f: ((In) -> Out) -> (In) -> Out) : (In) -> Out = {
    f(y(f))(it)
}

With that function you can do this (assuming executor returns String):

val lambda = y<Int, String> { f -> { value : Int -> executor(value, f) } }

I don't understand how that Y-combinator works, but it does the job 😛

[marstran]

Please don't write code like that in real life 😛

[Sam]

🙂