val isEven: (Int) -> Boolean = { i: Int -> i % 2 == 0 } val isOdd: (Int) -> Boolean = { it % 2 == 1 } fun filterIt1Long(i: Int, func: (Int) -> Boolean): List<Int> = buildList { for (v in (0..i)) { // (0..i) is inclusive if (func.invoke(v)) add(v) } } fun filterIt1Short(i: Int, func: (Int) -> Boolean): List<Int> = (0..i).filter(func) fun main() { println(filterIt1Long(8, isEven)) println(filterIt1Long(8, isOdd)) println(filterIt1Short(6, isEven)) println(filterIt1Short(6, isOdd)) println(filterIt1Short(4) { i: Int -> i % 2 == 0 }) println(filterIt1Short(4) { i: Int -> i % 2 != 0 }) println(filterIt1Short(4) { it % 2 == 0 }) println(filterIt1Short(4) { it % 2 != 0 }) }