it doesn't. Here testFilterType just returns the entire list and has no reified logic

getFilteredList<Int>( list, List<Any?>::testFilterType  )

    private fun <T> List<Any?>.testFilterType() : List<Any?> {

        val filteredList = mutableListOf<Any?>()

        forEach {
                filteredList.add( it )
        }

        return filteredList
    }

    private fun <T> getFilteredList( list : List<Any?>, filter : List<Any?>.() -> List<Any?> ) : List<Any?> {
        return list.filter()
    }

fun main(args: Array<String>) {
    val list = listOf(1, 2, 3)
    getFilteredList<Int>( list, List<Any?>::testFilterType  )
}

private inline fun <reified T> List<T>.testFilterType() : List<T> {

    val filteredList = mutableListOf<T>()

    forEach {
        filteredList.add( it )
    }

    return filteredList
}

private fun <T> getFilteredList( list : List<Any?>, filter : List<Any?>.() -> List<Any?> ) : List<Any?> {
    return list.filter()
}

this seems to compile, due to the expected return type T can get resolved, otherwise i have no clue how to specify T

Yeah, i was trying it on an android project using 1.2.71 Kotlin

kotlin already provides

filterIsInstance(...)

that was just to test reified and type parameters

oh ok

Yeah, that does it

and another tip: inside

testFilterType

you don't care about what type the original List contains, so you can leave that out with

List<*>.testFilterType(): List<T>

Got it