Comparing directly declaring lists vs initializer functions (using lambdas). The syntax is pretty decent except for maps but to be fair if you're doing this type of thing you should not be using maps.

collection_declare_vs_initializer_functions.kt

fun main() {
    // Both are the same
    val array1: Array<Int> = arrayOf(0, 1, 4, 9, 16) 
    val list1: List<Int> = listOf(0, 1, 4, 9, 16)
    val map1: Map<Int, Int> = mapOf(0 to 0, 1 to 1, 2 to 4, 3 to 9, 4 to 16)
    
    val array2: Array<Int> = Array(5) { it*it }
    val list2: List<Int> = List(5) {it*it}
    val map2: Map<Int, Int> = (Array(5) {it}).associate {it to it*it}
}

Note: Kotlin type inference is so good this entire code works without Type declarations.

    val array1 = arrayOf(0, 1, 4, 9, 16)
    val list1 = listOf(0, 1, 4, 9, 16)
    val map1 = mapOf(0 to 0, 1 to 1, 2 to 4, 3 to 9, 4 to 16)
    
    val array2 = Array(5) { it*it }
    val list2= List(5) {it*it}
    val map2 = (Array(5) {it}).associate {it to it*it}

MIT License