Kotlin multiple receiver ordering

receivers.kt

// Improving the ergonomics of dual receivers while we wait for
// context receivers

// This has a method with two receivers
class Thing {
    fun Context.foo(s: String): Int {
        // pretend it needs a Context for some reason
        return s.length
    }
}

interface Context

fun demo() {
    // given a thing and a context
    val thing = Thing()
    val context = object : Context {}

    // we would like to do this
    with(context) {
        // val i: Int = thing.foo("banana") doesn't compile
    }

    // but we have to do this, which is confusing
    with(thing) {
        val i: Int = context.foo("banana")
    }

    // run gets us closer
    with(context) {
        val i: Int = thing.run { foo("banana") }
    }

    // we can elide run with invoke
    operator fun <T, R> T.invoke(block: (T).() -> R): R = run(block)

    // getting us closer to the thing we wanted to say
    with(context) {
        val i: Int = thing { foo("banana") }
    }
}