I just learned that when defining a higher order f...

# getting-started

[Uberunix]

I just learned that when defining a higher order function, the parameters for the secondary functions can be declared nullable to make supplying them every time optional.

fun trickOrTreat(isTrick: Boolean, extraTreat: ((Int) -> String)?): () -> Unit {
    if (isTrick) {
        return trick
    } else {
        if (extraTreat != null) {
            println(extraTreat(5))
        }
        return treat
    }
}

Is this actually common or good practice?

[Youssef Shoaib [MOD]]

It prevents inline ing, for one, which is annoying. Having a default lambda is probably the better option. joinToString does the same thing that you do there, and it's very annoying

[Uberunix]

That's very helpful, thank you!

[Youssef Shoaib [MOD]]

You can also do:

fun trickOrTreat(isTrick: Boolean): () -> Unit = if (isTrick) trick else treat
fun trickOrTreat(isTrick: Boolean, extraTreat: (Int) -> String): () -> Unit = if (isTrick) trick else {
  println(extraTreat(5))
  treat
}

[Uberunix]

Ah, so you're saying that, like variables, I can actually define function bodies based on the results of a conditional statement?

[Uberunix]

Wait this is also an example of function overloading right? Is that what you actually wanted me to see?

[Youssef Shoaib [MOD]]

Yes the overloading was the point. I wrote it as a single-expression function out of laziness lol!

[Uberunix]

Haha! Love it. Thank you, sir!

[Nicolai C.]

I've used it a handful of times in some of my DSLs

[loke]

Why not just do something like:

fun trickOrTreat(extraTreat: (Int)->String = {trick}): String {
    return extraTreat(1234)
}

Then you can either call it without arguments, thus getting the default: trickOrTreat(), or you cal call it with a function, to get that result: trickOrTreat { "abc" }