I've been struggling to figure out how do you flatten nested outputs. For example, I want to call apply on some String values and a different type. It appears that the Java SDK only allows a single type on the parameters passed to

Output.all

so I have to nest multiple calls to apply or

Output.all

and then my results ends up something like

Output<Output<Output<String>>>

. I there a way to flatten this to

Output<String>

? Also, is there any way to block and get the value of an Output? I'm using some cross stack references and it would simplify things if I could block to get the actual values of the outputs from the stack reference.

Sure, you can do

o.apply(x => x)

to flatten

I saw that recommendation somewhere but when I tried that I seemed to still get back a nested output. I'm using the experimental Kotlin support but wasn't sure if that'd make a difference.

Each apply removes one level of nesting

Thanks for your help! I was definitely doing something wrong as it's working as you suggested. I wonder how you could automatically flatten it multiple levels. Maybe multiple method with a different signature?

fun <T> flatten(output: Output<Output<T>>): Output<T> {
    return output.apply { it }
}

fun <T> flatten(output: Output<Output<Output<T>>>): Output<T> {
    return output.apply { it }.apply { it }
}

fun <T> flatten(output: Output<Output<Output<Output<T>>>>): Output<T> {
    return output.apply { it }.apply { it }.apply { it }
}

// etc

Might be worth a try, I don't code Java daily but I recall it had some issues at the intersection of generics and overloads, so this might need to be flatten1/flatten2/flatten3