Why is this not allowed?

val map: Map<String, Int>? = mutableMapOf("one" to 3)
        map?.["one"] // <- Why is this not allowed?
        map?.get("one") // <- Which is equivalent to this, which works

Use map?["one"] Without the dot

Still doesn’t work, here is Kotlin Playground for it: https://pl.kotl.in/IxeuOxPo6

That doesn't compile

There is a long standing issue for it (unfortunately it doesn't look like it has any traction): https://youtrack.jetbrains.com/issue/KT-8799

You can't use this access syntax [] on a nullable receiver either for map or array only ?.get