Kotlin cannot infer type of Function with method reference

Question

why in the example below, with mapTwo Kotlin can't infer the type of a ?

fun <U> mapOne(f: (Int) -> U): U = TODO()
fun <U> mapTwo(f: Function<Int, U>): U = TODO()

fun <T> mapper(a: T): List<T> = TODO()

fun main() {
    mapOne(::mapper)
    mapTwo(::mapper) //won 't compile
}

IlyaMuravjov · Accepted Answer · 2019-10-29 23:49:31Z

1

Type inference is not the cause of a compilation error. mapTwo<List<Int>>(::mapper) will not compile either because of ::mapper having the type (T) -> List<T> (KFunction1<T, List<T>>), which is not assignable to Function<Int, U>.

answered Oct 29, 2019 at 23:49

IlyaMuravjov

2,5221 gold badge12 silver badges29 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Kotlin cannot infer type of Function with method reference

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related