JuniorTheoryCommon

What does the program print?

KOTLIN

fun main() {
    val double = { x: Int -> x * 2 }
    val inc: (Int) -> Int = { it + 1 }
    println(double(inc(3)))
}

Expecting 7: reading the line left to right. The inner call runs first: inc(3) gives 4, and only then double(4) gives 8.
Expecting it to need a declaration somewhere: a lambda with one parameter gets the name it for it, so { it + 1 } means the same as { x -> x + 1 }.

JuniorTheoryCommon

KOTLIN

fun main() {
    val double = { x: Int -> x * 2 }
    val inc: (Int) -> Int = { it + 1 }
    println(double(inc(3)))
}

Expecting 7: reading the line left to right. The inner call runs first: inc(3) gives 4, and only then double(4) gives 8.
Expecting it to need a declaration somewhere: a lambda with one parameter gets the name it for it, so { it + 1 } means the same as { x -> x + 1 }.