can i accept `>`, `<=`, etc as an argument t...

# announcements

[william]

can i accept >, <=, etc as an argument to a function?

[william]

i could def do a lambda like (Number, Number) -> Boolean) as an arg but not sure about using > directly

[Margarita Bobova]

@william Hello! Do you mean passing a boolean expression with > or <= to a function like below or something else?

fun foo(a: Boolean) {}

fun main() {
    val a = 5
    val b = 6
    foo(a >= b)
}

[Michael de Kaste]

@Margarita Bobova, I think he means passing an operator to a function and thus dynamically decide what to do

fun main(){
    foo(6,5){ a,b -> a > b}
}

fun foo(a: Int, b: Int, comparator: (Int, Int) -> Boolean) = comparator(a,b)

[Matteo Mirk]

You cannot pass a literal operator because it would be a syntactic error, neither pass a function reference because comparison operators are translated to compareTo() calls (https://kotlinlang.org/docs/reference/operator-overloading.html#comparison).

The shortest you can get is to declare comparison lambdas as variables and pass them:

fun test(x: Int, y: Int, f: (Int, Int) -> Boolean) = f(x, y)

val gt = { x: Int, y: Int -> x > y }
val gte = { x: Int, y: Int -> x >= y }
//etc...

fun main() {
    test(2, 1, gt)
    test(2, 2, gte)
}

[william]

thanks guys TIL they are translated to compareTo