Is there a way to have a function return a functio...

# getting-started

[kierans777]

Is there a way to have a function return a function with a generic type in Kotlin? I want to do

fun doSomething(): (Class<T>) -> T {}

However because lambda expressions can't have generic types, this doesn't compile for me.

[ephemient]

fun <T> doSomething(): (Class<T>) -> T

would be legal

[kierans777]

True, however I don't want to make doSomething generic.

[ephemient]

"(Class<T>) -> T for all possible T" is not a denotable type

[kierans777]

I think I'm going to have to decompose the problem differently

[ephemient]

fun interface DoSomething<T> : (Class<T>) -> T
fun doSomething(): DoSomething<*> {}

is also legal, but pretty awkward (it's not the lambda type itself, it's a subtype)

[ephemient]

that sort of wrapper is still a reasonable solution in some cases - e.g. how kotlin.coroutines.CoroutineContext/.Element/.Key is parameterized, or https://github.com/brutall/typedmap - but you do need something else to maintain the constraint

[randomcat]

If you're okay with a separate interface, why not
``````

[randomcat]

interface I {
    operator fun <T> invoke(klazz: Class<T>): T
}

[kierans777]

@randomcat Thanks for the suggestion. I also got some help from the #arrow channel and got the same suggestion. I updated my code yesterday (AEST) to use this and it works perfectly.

[randomcat]

ah, glad you figured it out