Is there a less ugly way to return function in Kotlin?

Question

This declaration works, but is not the most beautiful code. Is there a way to return functions less ugly? I tried (s: String) -> writer.println(s) but this didn't work.

val writeStuff: (PrintWriter) -> (String) -> Unit = {
    val writer = it
    val f: (String) -> Unit = {
        writer.println(it)
    }
    f
}
PrintWriter("test").use { writeStuff(it)("TEST") }

EDIT: a bit more concrete example:

val writeStuff: (PrintWriter) -> (String) -> Unit = { writer ->
    { writer.println(it) }
}

val sendStuff: (Any) -> (String) -> Unit = { sender ->
    { sender.equals(it) }
}

@Test fun test1() {
    val li = listOf("a", "b", "c")

    val process: List<(String) -> Unit> = 
        listOf(writeStuff(PrintWriter("a")), sendStuff(Object()))

    process.map { li.map(it) }
}

Answer 1

First, you can simplify your code using lambda syntax with explicit parameter and inlining val f:

val writeStuff: (PrintWriter) -> (String) -> Unit = { writer -> 
    { writer.println(it) } 
}

But since Kotlin supports local function declarations, you can even make writeStuff a local fun instead of a val.

This would lead to the following code:

fun writeStuff(writer: PrintWriter): (String) -> Unit {
    return { writer.println(it) }
}

Or, using the single expression syntax,

fun writeStuff(writer: PrintWriter): (String) -> Unit = { writer.println(it) }

The usage, however, will be the same:

PrintWriter("...").use { writeStuff(it)("...") }