I haven't looked into it much in the past few years so it is possible the inner class overhead on Android is not significant anymore, but a few years ago it was

I haven't looked into it much in the past few years so it is possible the inner class overhead on Android is not significant anymore, but a few years ago it was definitely something to watch out for on Dalvik. Again I wasn't being very clear, sorry about that: Kotlin doesn't always reify generics, but it can for functions you mark as inline if you want (it's useful!). Check out the inline function docs!