and the other way ```fun interface NullableEffect&...

# arrow

[carbaj0]

and the other way

fun interface NullableEffect<A> : Effect<A?> {
    ...

    suspend operator fun <E, B> Either<E, B>.invoke(): B =
        fold({  control().shift(null) }, ::identity)
}

val r1: Either<String, Int> = Right(1)
val r2: Either<String, Int> = Left("fail")
val r3: Either<String, Int> = Right(1)
val r4: Int? = 1

val composition2 = nullable {
    val a = r1()
    val b = r2()
    val c = r3()
    val d = r4()

    a + b + c + d
} // null