Given this code: ```println(intArrayOf() === intAr...

# stdlib

[Klitos Kyriacou]

Given this code:

println(intArrayOf() === intArrayOf())

We can see that intArrayOf() creates a new empty array each time it's called. By contrast, in C# the syntax [] is shorthand for Array.empty<>() which returns a preallocated empty array, thus not needing to do any heap allocation. What is the rationale for making xxxArrayOf() allocate a new object each time? An empty array is implicitly "immutable" (as there is nothing to mutate), so thread safety is not an issue.

[ephemient]

that's what newarray does in java

[ephemient]

btw arrays are rather special in Java, in that they know their own component type (although erased, because it predates generics):

arrayOf<Int>() as Array<Any> // succeeds, but is unsafe to write to because
(arrayOf(0) as Array<Any>)[0] = "" // throws java.lang.ArrayStoreException
arrayOf<Any>() as Array<Int> // throws java.lang.ClassCastException, **not** unchecked
arrayOf<List<Any>>() as Array<List<Int>> // succeeds…

so you cannot have a single static empty array for all types, you need to have one for every type (including every array type)

[ephemient]

if for some reason you really do need a single empty array per type, you can handle that yourself. https://pl.kotl.in/eSSlzXEfC
but it should be understandable why it's not something standard or built-in

[ephemient]

but in general, just don't use arrays. emptyList() is a singleton (not that it even needs to be to pass emptyList<Int>() == emptyList<Int>(), since it has structural equals)